Method for short-circuit test of split column of extra-high voltage transformer

Abstract

The application discloses a method for testing short circuit of a split column of an extra-high voltage transformer, and particularly comprises the following steps: processing a plurality of parallel columns of a transformer to be tested according to a test system to form n parts to be tested; and respectively performing high-medium short circuit test, high-low short circuit test and medium-low short circuit test on each part to be tested of the transformer to be tested. The method can quickly, effectively and accurately perform high-medium short circuit test, high-low short circuit test and medium-low short circuit test on the extra-high voltage transformer.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of transformer test, and particularly relates to a method for short-circuit test of a split-column ultra-high voltage transformer. BACKGROUND

[0002] Ultra-high voltage refers to power transmission technology with a voltage level of 1000 kV and above in alternating current and ±800 kV and above in direct current, which has technical advantages of large transmission capacity, long distance, high efficiency and low loss. Ultra-high voltage power transmission plays an important role in ensuring power supply, promoting clean energy development, improving the environment and enhancing the safety level of power grids.

[0003] An ultra-high voltage transformer is a core device in an ultra-high voltage power transmission network. The transformer will inevitably be subjected to the impact of short-circuit current during operation in the power transmission network. Whether the transformer can withstand the impact of short-circuit current without damage directly affects the operation safety of the power transmission line. The most effective and direct method to determine whether the transformer can withstand the impact of short-circuit current is to verify it through test.

[0004] However, it is difficult to directly test an ultra-high voltage transformer, so a method for short-circuit test of a split-column ultra-high voltage transformer is urgently needed. SUMMARY

[0005] To solve the above technical problems, the present application provides a method for short-circuit test of a split-column ultra-high voltage transformer.

[0006] To achieve the above purpose, the technical solution of the present application is as follows:

[0007] The present application discloses a method for short-circuit test of a split-column ultra-high voltage transformer, comprising the following steps:

[0008] STEP1: Process multiple parallel columns of the transformer to be tested according to the test system, to form n parts to be tested;

[0009] STEP2: Perform high and short circuit test, high and low short circuit test and medium and low short circuit test on each part to be tested of the transformer to be tested.

[0010] On the basis of the above technical solution, the following improvements can be made:

[0011] As a preferred solution, STEP1 specifically includes the following content:

[0012] Disconnect the middle voltage A m from the parallel connection of the adjacent column winding inside the transformer to be tested, and divide it into A m1 terminal to A mn terminal, and lead out n middle voltage terminals, n≥2, n is an integer;

[0013] or the low-voltage X terminal of the transformer to be tested is divided into X1 terminal to X k terminal, into k low-voltage terminal leads, k≥2, k is an integer.

[0014] As a preferred scheme, when the medium-voltage A m lead is divided into n medium-voltage terminals, the method of high-low short circuit test is as follows: the A terminal of the transformer to be tested is connected to the high-voltage system, the X terminal is connected to the low-voltage system, and the medium-voltage A mi terminal of the i-th part to be tested is open; the low-voltage a terminal and the low-voltage x terminal are short-circuited, i∈[1, n].

[0015] As a preferred scheme, when the medium-voltage A m lead is divided into n medium-voltage terminals, the method of high-low short circuit test is as follows: the A terminal of the transformer to be tested is connected to the high-voltage system, the X terminal is connected to the low-voltage system, and the medium-voltage A mi terminal of the i-th part to be tested is open; the low-voltage a terminal and the low-voltage x terminal are short-circuited, i∈[1, n].

[0016] As a preferred scheme, when the medium-voltage A m lead is divided into n medium-voltage terminals, the method of high-low short circuit test is as follows: the A terminal of the transformer to be tested is connected to the high-voltage system, the X terminal is connected to the low-voltage system, and the medium-voltage A mi terminal of the i-th part to be tested is open; the low-voltage a terminal and the low-voltage x terminal are short-circuited, i∈[1, n].

[0017] As a preferred scheme, when the low-voltage X terminal is divided into k low-voltage terminals, the method of high-low short circuit test is as follows: the A terminal of the transformer to be tested is connected to the high-voltage system, the X j terminal of the j-th part to be tested and the A m terminal are short-circuited and then connected to the low-voltage system; the low-voltage a terminal and the low-voltage x terminal are open, j∈[1, k].

[0018] As a preferred scheme, when the low-voltage X terminal is divided into k low-voltage terminals, the method of high-low short circuit test is as follows: the A terminal of the transformer to be tested is connected to the high-voltage system, the X j terminal of the j-th part to be tested is connected to the low-voltage system, and the A m terminal is open; the low-voltage a terminal and the low-voltage x terminal are short-circuited, j∈[1, k].

[0019] As a preferred scheme, when the low-voltage X terminal is divided into k low-voltage terminals, the method of high-low short circuit test is as follows: the A terminal of the transformer to be tested is connected to the high-voltage system, the X j terminal of the j-th part to be tested is connected to the low-voltage system, and the A m terminal is connected to the high-voltage system; the low-voltage a terminal and the low-voltage x terminal are short-circuited, j∈[1, k].

[0020] The application discloses a method for short-circuit test of a UHV transformer, and the method can quickly, effectively and accurately perform high-voltage short-circuit test, high-low voltage short-circuit test and medium-low voltage short-circuit test on the UHV transformer, and solves the problem that the existing test system has small capacity and cannot directly perform short-circuit test on the UHV transformer. BRIEF DESCRIPTION OF DRAWINGS

[0021] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed to be used in the embodiments will be briefly introduced as follows. It should be understood that the following drawings only show some of the embodiments of the present application, and therefore should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can also be obtained without creative labor on the basis of these drawings.

[0022] Figure 1 The flow chart of the method for short-circuit test of a UHV transformer is provided for the embodiments of the present application.

[0023] Figure 2 The schematic diagram of high-medium short-circuit test wiring is provided for the embodiments of the present application.

[0024] Figure 3 The schematic diagram of high-low short-circuit test wiring is provided for the embodiments of the present application.

[0025] Figure 4 The schematic diagram of medium-low short-circuit test wiring is provided for the embodiments of the present application.

[0026] Figure 5 The schematic diagram of test working condition wiring of a three-winding transformer is provided for the embodiments of the present application.

[0027] Figure 6 The circuit diagram of a short-circuit bearing capacity test system of a UHV transformer is provided for the embodiments of the present application. DETAILED DESCRIPTION

[0028] The preferred embodiments of the present application will be described in detail below with reference to the drawings.

[0029] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all the other embodiments obtained by those skilled in the art without creative labor fall within the scope of the present application.

[0030] The use of ordinal numbers "first", "second", "third" and the like to describe generic objects merely indicates different instances of similar objects and is not intended to imply that the objects so described must be in a given order, spatially, temporally, ordered in any other manner, or otherwise.

[0031] In addition, the expression "comprising" elements is an "open" expression indicating the presence of the corresponding components only, and should not be interpreted as excluding additional components.

[0032] To achieve the purpose of the present application, some embodiments of the method for testing the short-circuit of the split column of the extra-high voltage transformer include the following steps as shown in Figure 1 The method for testing the short-circuit of the split column of the extra-high voltage transformer includes the following steps:

[0033] STEP1: According to the test system, the two parallel columns of the transformer to be tested are processed to form two test parts, and one column is a test part.

[0034] STEP2: High, low and medium short-circuit tests are respectively performed on each column of the transformer to be tested.

[0035] It is worth noting that this embodiment takes a 1000MVA / 1000kV transformer to be tested with two columns as an example, but the protection scope of the present application is not limited to the transformer to be tested with two columns, each column having a capacity of 500MVA.

[0036] The short-circuit withstand test mainly tests the withstand ability of the electric power between the high, low and medium windings of a single column, so the short-circuit test is respectively performed on the two columns of the 1000MVA transformer.

[0037] STEP1 specifically includes the following contents: disconnecting the medium voltage A m terminal of the transformer to be tested from the parallel connection of the internal adjacent column winding, and dividing it into the medium voltage A m1 terminal and the medium voltage A m2 terminal.

[0038] Further, as shown in Figure 2 , the method for testing the high short-circuit of the first column of the transformer to be tested is as follows: connecting the A terminal of the transformer to be tested to the high voltage system, short-circuiting the X terminal and the medium voltage A m1 terminal of the first column and connecting it to the low voltage system; and opening the low voltage a terminal and the low voltage x terminal.

[0039] Further, as shown in Figure 3 , the method for testing the high-low short-circuit of the first column of the transformer to be tested is as follows: connecting the A terminal of the transformer to be tested to the high voltage system, connecting the X terminal to the low voltage system, opening the medium voltage A m1 terminal of the first column; and short-circuiting the low voltage a terminal and the low voltage x terminal.

[0040] Further, as shown in Figure 4 the method for the middle-low short circuit test of the first column of the transformer to be tested is as follows: the A end of the transformer to be tested is opened, the X end is connected to the low-voltage system, the middle-voltage A m1 end of the first column is connected to the high-voltage system; the low-voltage a end and the low-voltage x end are short-circuited.

[0041] Similarly, the method for the short circuit test of the second column of the transformer to be tested is as follows:

[0042] the method for the high-middle short circuit test of the second column of the transformer to be tested is as follows: the A end of the transformer to be tested is connected to the high-voltage system, the X end and the middle-voltage A m2 end of the second column are short-circuited and then connected to the low-voltage system; the low-voltage a end and the low-voltage x end are opened.

[0043] the method for the high-low short circuit test of the second column of the transformer to be tested is as follows: the A end of the transformer to be tested is connected to the high-voltage system, the X end is connected to the low-voltage system, the middle-voltage A m2 end of the second column is opened; the low-voltage a end and the low-voltage x end are short-circuited.

[0044] the method for the middle-low short circuit test of the second column of the transformer to be tested is as follows: the A end of the transformer to be tested is opened, the X end is connected to the low-voltage system, the middle-voltage A m2 end of the second column is connected to the high-voltage system; the low-voltage a end and the low-voltage x end are short-circuited.

[0045] As shown in Figure 5 , the three-winding power transformer operates on the network, usually with the high-voltage side connected to the network, the middle-voltage side connected to the network, and the low-voltage side connected to the load. When selecting the test working condition of the three-winding transformer, there are usually the following situations.

[0046] If a short circuit fault occurs at the middle-voltage side outgoing line end, the short circuit current is generated in the high-middle voltage winding, and if a short circuit fault occurs at the high-voltage side outgoing line end, the short circuit current is also generated in the high-middle voltage winding. These two fault conditions can be verified by the high-middle short circuit test working condition.

[0047] If a short circuit fault occurs at the low-voltage side outgoing line end, the high-middle voltage winding supplies power to the low-voltage winding at this time, and the high-to-low short circuit impedance of the transformer is greater than the middle-to-low short circuit impedance, so the short circuit current is mainly generated in the middle-low voltage winding. This fault condition can be verified by the middle-low short circuit test working condition.

[0048] The calculation of the specific short circuit current also determines the system apparent capacity of the middle-voltage network, whether it is connected to the network or parallel operation of several same type transformers. The selection of the operation mode has a great influence on the short circuit current.

[0049] It is worth noting that in other embodiments.

[0050] The step 1 specifically comprises the following: the low-voltage X end of the transformer to be tested is divided into a low-voltage X1 end and a low-voltage X2 end.

[0051] Further, the high-low short circuit test method for the first column of the transformer to be tested is as follows: the A end of the transformer to be tested is connected to the high-voltage system, the X1 end of the first column is connected to the low-voltage system, the A end is open circuit, and the low-voltage a end and the low-voltage x end are short-circuited. m

[0052] Further, the high-low short circuit test method for the first column of the transformer to be tested is as follows: the A end of the transformer to be tested is connected to the high-voltage system, the X1 end of the first column is connected to the low-voltage system, the A end is open circuit, and the low-voltage a end and the low-voltage x end are short-circuited. m

[0053] Further, the high-low short circuit test method for the first column of the transformer to be tested is as follows: the A end of the transformer to be tested is connected to the high-voltage system, the X1 end of the first column is connected to the low-voltage system, the A end is open circuit, and the low-voltage a end and the low-voltage x end are short-circuited. m

[0054] The short circuit test method for the second column of the transformer to be tested is as follows:

[0055] The high-low short circuit test method for the second column of the transformer to be tested is as follows: the A end of the transformer to be tested is connected to the high-voltage system, the X2 end of the second column is connected to the low-voltage system, the A end is open circuit, and the low-voltage a end and the low-voltage x end are short-circuited. m

[0056] The high-low short circuit test method for the second column of the transformer to be tested is as follows: the A end of the transformer to be tested is connected to the high-voltage system, the X2 end of the second column is connected to the low-voltage system, the A end is open circuit, and the low-voltage a end and the low-voltage x end are short-circuited. m

[0057] The high-low short circuit test method for the second column of the transformer to be tested is as follows: the A end of the transformer to be tested is connected to the high-voltage system, the X2 end of the second column is connected to the low-voltage system, the A end is open circuit, and the low-voltage a end and the low-voltage x end are short-circuited. m

[0058] In order to facilitate the understanding of the present application, a UHV transformer short circuit withstand test system is introduced below, which adopts the column short circuit test method disclosed in the present application.

[0059] As shown in Figure 6 , the UHV transformer short circuit withstand test system comprises a group of power supply modules, a group of first voltage boosting modules, and two groups of second voltage boosting modules.

[0060] ​​​​​​The power supply module comprises: five generators G1 to G5, a current limiting reactor CLR and a closing phase selector switch HQ.

[0061] The first voltage boosting module comprises: first voltage boosting transformers DA1 to DA6.

[0062] The primary sides of the first voltage boosting transformers DA1 to DA6 are connected in parallel and electrically connected with the power supply module, the secondary sides of the first voltage boosting transformers DA1 to DA6 are connected in reverse series in sequence, and the secondary side of the first voltage boosting transformer DA1 is electrically connected with a first test end of the transformer to be tested. The first test end can be, but is not limited to, an x end of the transformer to be tested.

[0063] One of the second voltage boosting modules comprises: second voltage boosting transformers DB1 to DB2 and isolation voltage boosting transformers DC1 to DC2.

[0064] The primary sides of the isolation voltage boosting transformers DC1 to DC2 are connected in parallel and electrically connected with the power supply module, the secondary sides of the isolation voltage boosting transformers DC1 to DC2 are connected in parallel, and the parallel connection is used to supply power to the primary sides of the second voltage boosting transformers DB1 to DB2.

[0065] The primary sides of the second voltage boosting transformers DB1 to DB2 are connected in series, the secondary sides of the second voltage boosting transformers DB1 to DB2 are connected in series, the secondary side of the second voltage boosting transformer DB1 is electrically connected with the secondary side of the first voltage boosting transformer DA6, and the secondary side of the second voltage boosting transformer DB2 is electrically connected with the secondary side of the second voltage boosting transformer DB3 in another second voltage boosting module.

[0066] The other second voltage boosting module comprises: second voltage boosting transformers DB3 to DB4 and isolation voltage boosting transformers DC3 to DC4.

[0067] The primary sides of the isolation voltage boosting transformers DC3 to DC4 are connected in parallel and electrically connected with the power supply module, the secondary sides of the isolation voltage boosting transformers DC3 to DC4 are connected in parallel, and the parallel connection is used to supply power to the primary sides of the second voltage boosting transformers DB3 to DB4.

[0068] The primary side of the second step-up transformer DB3 to the second step-up transformer DB4 is connected in series, the secondary side of the second step-up transformer DB3 to the second step-up transformer DB4 is connected in series, the secondary side of the second step-up transformer DB3 is electrically connected with the secondary side of the second step-up transformer DB2 in the last group of second step-up modules, and the secondary side of the second step-up transformer DB4 is electrically connected with the second test end of the transformer to be tested. The second test end can be, but is not limited to, the A end of the transformer to be tested.

[0069] The transformer to be tested is a 1000 MVA / 1000 kV extra-high voltage transformer.

[0070] The generator is a DSF-6500 impact generator, and five 6500 MVA impact generators are connected in parallel to provide a short-time three-phase 32500 MVA and a two-phase 18500 MVA test power supply.

[0071] The first step-up transformers DA1 to DA6 and the isolation step-up transformers DC1 to DC4 are YD-120000 / 220 impact transformers, specifically test transformers with a short-time capacity of 1500 MVA.

[0072] The second step-up transformers DB1 to DB4 are YLD-120000 / 750 impact transformers, specifically test transformers with a short-time capacity of 1200 MVA.

[0073] The series connection point between the secondary side of the first step-up transformer DA1 and the secondary side of the first step-up transformer DA2 is electrically connected with the tank shell of the transformer to be tested. The series connection point between the secondary side of the first step-up transformer DA3 and the secondary side of the first step-up transformer DA4 is grounded. The transformer to be tested is arranged on the insulation platform IP. The second step-up transformer DB3 and the second step-up transformer DB4 are arranged on the insulation platform IP.

[0074] The second test end of the transformer to be tested is electrically connected with the second step-up transformer DB4 in the second step-up module through the disconnecting circuit breakers FQ1 and FQ2.

[0075] The arrester ARR is arranged at a suitable position in the circuit.

[0076] The steps of using the above test system to perform high-voltage and intermediate-voltage tests on the first column of the transformer to be tested are specifically introduced as follows.

[0077] S1, place the transformer to be tested S on the insulation platform IP, and connect the low-voltage A m1 terminal of the first column of the transformer to be tested S to the X terminal through a conductor with sufficient cross section, and open the low-voltage terminals a and x;

[0078] S2, the second step-up transformer DB3 and the second step-up transformer DB4 are placed on the insulating platform IP, the second step-up transformer DB3 and the second step-up transformer DB4 are insulated from the ground, and can withstand a voltage of 175 kV;

[0079] S3, the X terminal of the first step-up transformer DA1 is connected to the X terminal of the test transformer, the A terminal of the first step-up transformer DA1 is connected to the S tank of the test transformer, and the A terminal of the second step-up transformer DB4 is connected to the A terminal of the test transformer through the disconnecting circuit breaker FQ1 and the disconnecting circuit breaker FQ2;

[0080] S4, the generators G1 to G5 are started to the rated speed, the backup breaker BD and the parallel connection circuit breaker PD are pre-connected, and after the five generators are balanced through the parallel connection reactor PR, the same voltage and the same speed are reached;

[0081] S5, the current limiting reactor CLR value is adjusted, the fault current of the generator is controlled to be 80 kA, the disconnecting circuit breaker FQ1 and the disconnecting circuit breaker FQ2 are closed, the closing phase selector HQ is opened, the generator over-excitation input multiple and input time are adjusted, and the generator regulating time and de-excitation time are adjusted;

[0082] S6, the reactance value of the first column of the test transformer before the test is measured;

[0083] S7, the generator is boosted to a first preset value, the closing phase selector HQ is closed, the disconnecting circuit breaker FQ1 and the disconnecting circuit breaker FQ2 are opened after 250 ms, and the adjustment test of 50% current is completed;

[0084] S8, the disconnecting circuit breaker FQ1 and the disconnecting circuit breaker FQ2 are closed, and the closing phase selector HQ is opened;

[0085] S9, the generator is boosted to a second preset value, the closing phase selector HQ is closed, the disconnecting circuit breaker FQ1 and the disconnecting circuit breaker FQ2 are opened after 250 ms, and the first formal test of 100% current is completed;

[0086] S10, the disconnecting circuit breaker FQ1 and the disconnecting circuit breaker FQ2 are closed, and the closing phase selector HQ is opened;

[0087] S11, the reactance value of the test transformer S is measured, and compared with the reactance value of the first column of the test transformer S before the test, to determine whether it meets the standard requirements;

[0088] If it meets the requirements, S12 is entered;

[0089] If it does not meet the requirements, the test is stopped;

[0090] S12, the first column of the test transformer S is changed to a tap, and the reactance value of the first column of the test transformer S before the next test is measured.

[0091] S13, repeating steps S7-S12, completing the second 100% current formal test;

[0092] S14, repeating steps S7-S12, completing the third 100% current formal test.

[0093] The method of the 1000MVA extra-high voltage transformer column test solves the problem of test power capacity, and the 1500MVA extra-high voltage transformer with the largest capacity in the extra-high voltage transmission system can also be verified by using the column test method.

[0094] The application makes the short circuit withstand capability test of the extra-high voltage transformer possible, and provides protection for the safe operation of the extra-high voltage network.

[0095] The application discloses a column short circuit test method of an extra-high voltage transformer, and the method can quickly, effectively and accurately perform high and short circuit test, high and low short circuit test and medium and low short circuit test on the transformer to be tested, and solves the problem that the existing test system has small capacity and cannot directly perform short circuit test on the extra-high voltage transformer.

[0096] The above examples are only for illustrating the technical concept and characteristics of the application, and the purpose is to enable those skilled in the art to understand the content of the application and implement it, and cannot limit the protection scope of the application, and equivalent changes or modifications according to the spirit and essence of the application should be covered in the protection scope of the application.

Claims

1. A method of short-circuit test of a separate column of an extra-high voltage transformer, characterized in that, The method comprises the following steps: STEP1: according to the test system, process multiple parallel columns of the transformer to be tested to form n parts to be tested; STEP2: respectively perform high, medium and short circuit test, high and low short circuit test and medium and low short circuit test on each part to be tested of the transformer to be tested; STEP1 specifically includes the following contents: The middle voltage A of the transformer to be tested is connected to the middle voltage B of the transformer to be tested through the middle voltage A m The lead wire is disconnected from the parallel position of the internal adjacent column winding, and divided into A m1 The end is connected to the A mn The end, divided into n middle voltage terminal leads, n≥2, n is an integer; or the low-voltage X end of the transformer to be tested is divided into X1 end to X k end, into k low-voltage terminal leads, k≥2, k is an integer; When the medium voltage A m When the lead is divided into n medium voltage terminals, the method of high and short circuit test is as follows: the A terminal of the transformer to be tested is connected to the high voltage system, the X terminal and the medium voltage A mi terminal of the i-th part to be tested are short-circuited and then connected to the low voltage system; The low-voltage a end and the low-voltage x end are open, i ∈ [1, n]; or, When the medium voltage A m When the lead is divided into n medium voltage terminals, the method of high-low short circuit test is as follows: the A terminal of the transformer to be tested is connected to the high voltage system, the X terminal is connected to the low voltage system, the medium voltage A mi terminal of the i-th part to be tested is open circuit, the low voltage a terminal and the low voltage x terminal are short-circuited, i∈[1, n]; or, When the medium voltage A m When the lead is divided into n medium voltage terminals, the method of medium-low short circuit test is as follows: the A end of the transformer to be tested is opened, the X end is connected to the low voltage system, the medium voltage A mi end of the i-th part to be tested is connected to the high voltage system; the low voltage a end and the low voltage x end are short-circuited, i∈[1, n]; or, When the low-voltage X terminal is divided into k low-voltage terminals, the method for high-voltage short-circuit testing is as follows: Connect the A terminal of the transformer under test to the high-voltage system, and the X terminal of the j-th section under test... j End and A m Short-circuit the terminal and connect to the low-voltage system; open circuit between low-voltage terminal a and low-voltage terminal x, j∈[1,k]; or, When the low-voltage X terminal is divided into k low-voltage terminals, the method of high-low short circuit test is as follows: the A terminal of the transformer to be tested is connected to the high-voltage system, the X terminal of the jth part to be tested is connected to the low-voltage system, the A terminal is open circuit, the low-voltage a terminal and the low-voltage x terminal are short-circuited, j∈[1, k]; or, j m the A terminal of the transformer to be tested is connected to the high-voltage system, the X terminal of the jth part to be tested is connected to the low-voltage system, the A terminal is open circuit, the low-voltage a terminal and the low-voltage x terminal are short-circuited, j∈[1, k]; or,​ When the low-voltage X terminal is divided into k low-voltage terminals, the method of the middle-low short circuit test is as follows: the A terminal of the transformer to be tested is opened, the X terminal of the jth part to be tested is connected to the low-voltage system, the A terminal of the jth part to be tested is connected to the high-voltage system, the low-voltage a terminal and the low-voltage x terminal are short-circuited, j∈[1, k]. j m ​​

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