Method and device for measuring DC resistance of converter winding without disassembling tubular busbar

Abstract

The present invention provides a method for measuring the DC resistance of a converter transformer winding without disassembling a tubular busbar, which belongs to the field of transformer fault diagnosis; the method comprises: removing the soft wire between the converter transformer tubular busbar and the overhead line and the grounding copper bar; separating the valve-side grounding knife switch of the converter transformer; connecting the measuring device to the tubular busbar and the converter transformer winding; connecting the three-phase grid-side tube busbars respectively through the measuring device to measure the DC resistance of each phase winding, and calculating the grid-side valve-side resistance reduction value and ratio; evaluating the grid-side valve-side winding defects according to the grid-side valve-side resistance reduction value and ratio. The present invention also provides a device for measuring the DC resistance of a converter transformer winding without disassembling a tubular busbar. The present invention adopts a method for testing the DC resistance of the winding without disassembling the tubular busbar, which greatly reduces the maintenance cycle, reduces the maintenance cost, avoids the risk of safety maintenance, facilitates testing, and improves the testing efficiency.

Description

Technical Field

[0001] The invention relates to the technical field of lean maintenance preventive testing of large converter transformers, and in particular to a method and device for measuring the DC resistance of a converter transformer winding without disassembling a tubular busbar. Background Art

[0002] As the core component of the power transmission and transformation system, the insulation performance of large converter transformers is directly related to the safe and stable operation of the power system. Preventive test evaluation as a routine maintenance method is an important method to support the reliability evaluation of power equipment. However, in recent years, converter stations have generally carried out evaluation work in the form of exhaustive comparison of on-site tests. This form of evaluation work has exposed the shortcomings of long time cycle, high safety risks, high maintenance costs and poor emergency measures. In addition, the exhaustive method is the main evaluation method, and the workload of each evaluation is huge. As the number of power outage requirements of converter stations decreases, this form of evaluation is difficult to maintain.

[0003] The measurement of DC resistance of transformer windings is an important test item in power production. It can reflect defects such as short circuit between winding turns, broken strands, contact status of tap changers, differences in wire resistance, and poor contact of joints. It is also an effective means to determine whether the DC resistance of each phase winding is balanced and whether the voltage regulating switch position is correct. The current test method for DC resistance of converter transformer windings requires the removal of a large number of tubular busbars, which is difficult to remove and requires a large amount of work. The overall maintenance cycle is long, which seriously affects the overall operation of the converter station.

[0004] Therefore, there is an urgent need for a method that can measure the DC resistance of the converter transformer winding without disassembling the tubular busbar, which is conducive to improving the lean maintenance level of electrical equipment. Summary of the invention

[0005] In order to address the deficiencies of the above-mentioned prior art, the present invention provides a method and device for measuring the DC resistance of a converter transformer winding without disassembling a tubular busbar, which greatly improves the lean maintenance of converter transformers in UHV converter stations and hub substations and the reliability of equipment, and can greatly reduce the maintenance cycle, reduce maintenance costs, and avoid safety maintenance risks and poor emergency measures.

[0006] The purpose of the present invention can be achieved by adopting the following technical solutions:

[0007] The present invention provides a method for measuring the DC resistance of a commutation transformer winding without disassembling a tubular busbar, comprising:

[0008] Remove the flexible wires between the converter transformer tube busbar, overhead line and grounding copper bar; separate the grounding knife switch on the valve side of the converter transformer;

[0009] Connect the measuring device to the tubular busbar and the commutation transformer winding;

[0010] The three-phase grid-side pipe mother is connected to measure the DC resistance of each phase winding through the measuring device, and the grid-side valve-side resistance conversion value and ratio are calculated;

[0011] The defects of the grid-side valve-side winding are evaluated based on the calculated value and ratio of the grid-side valve-side resistance.

[0012] As a further technical solution of the present invention, the measuring device is connected with the tubular busbar and the converter transformer winding; specifically comprising:

[0013] Carry out wiring according to the wiring diagram. One end of the current excitation harness is connected to the tubular busbar, and the other end is connected to the current interface of the measuring host. One end of the voltage response harness is connected to the soft connection closest to the transformer winding terminal, and the other end is connected to the voltage interface of the measuring host. The jaws of the current measuring clamp are clamped on the neutral point soft connection on the grid side of the test transformer.

[0014] As a further technical solution of the present invention, the three-phase grid-side pipe mother is connected respectively by a measuring device to measure and calculate the grid-side and valve-side resistance of each phase winding; specifically, it includes:

[0015] The measuring device provides DC excitation to test the grid-side voltage, valve-side voltage, and loop current, completing the grid-side voltage U L , valve side voltage U V The current measuring clamp completes the measurement of the loop current I; the measuring device completes the calculation of the single-phase DC resistance R of the grid-side winding L =U L / I, complete the calculation of the phase-to-phase DC resistance of the valve side winding R v =U v / I, complete the calculation of the resistance ratio of the network side to the valve side d = R L / R v .

[0016] As a further technical solution of the present invention, the evaluation of the grid-side valve-side winding defect according to the grid-side valve-side resistance reduction value and ratio specifically includes:

[0017] Calculate the initial value difference of the single-phase DC resistance of the grid-side winding. When the initial value difference of the single-phase DC resistance of the grid-side winding is greater than the first set value, it is judged that the grid-side winding has poor contact; when the initial value difference of the single-phase DC resistance of the grid-side winding is less than the second set value, it is judged that the grid-side winding has an inter-turn short circuit.

[0018] The initial value difference of the single-phase DC resistance of the valve side winding is calculated. When the initial value difference of the single-phase DC resistance of the valve side winding is greater than the third set value, it is judged that the valve side winding has poor contact; when the initial value difference of the single-phase DC resistance of the valve side winding is less than the fourth set value, it is judged that the valve side winding has a short circuit between turns.

[0019] As a further technical solution of the present invention, the initial value difference of the single-phase DC resistance of the grid-side winding is calculated as follows:

[0020] Grid-side winding single-phase DC resistance R L Initial value difference ΔR L Evaluation of R L Calculate from the test temperature to 75°C using R L(75) Compared with the factory test results R L(o) Make a comparison;

[0021]

[0022] The initial value difference of the single-phase DC resistance of the valve-side winding is calculated as follows:

[0023] Single-phase DC resistance of valve side winding R V Initial value difference ΔR v Evaluation, R V Calculate from the test temperature to 75°C using R V(75) Compared with the factory test results R V(o) Make a comparison;

[0024]

[0025] As a further technical solution of the present invention, the first set value is 2%, the second set value is -2%, the third set value is 1%, and the fourth set value is -1%.

[0026] As a further technical solution of the present invention, it also includes: verifying the evaluation result by comparing the resistance of the network side with the valve side; specifically including:

[0027] Evaluation of the initial value difference Δd of the network side valve side resistance ratio d, using d and the factory test result d (o) Make a comparison;

[0028]

[0029] When Δd≥2%, it indicates poor contact of the grid-side winding; when Δd≤-2%, it indicates short circuit between turns of the grid-side winding;

[0030] When Δd≤-1%, the valve side winding has poor contact; when Δd≥1%, the valve side winding has a short circuit between turns.

[0031] As a further technical solution of the present invention, the jaws of the current measuring clamp are clamped on the central point soft connection of the test converter transformer grid side and are closer to the winding terminal than the connection point of the voltage response harness.

[0032] The present invention also provides a device for measuring the DC resistance of a converter transformer winding without disassembling a tubular busbar, comprising:

[0033] A shell, wherein a current excitation module, a current measurement module, a voltage measurement module, and a controller are arranged inside the shell; an operation panel is arranged on the shell, and a current excitation terminal, a voltage response terminal, a current measurement clamp interface, and a display screen are arranged on the operation panel, the current excitation terminal is connected to the output end of the current excitation module, the voltage measurement module is connected to the voltage response terminal, and the current measurement clamp interface is connected to the current measurement module; the current excitation module, the current measurement module, and the voltage measurement module are connected to the controller; and the output end of the controller is connected to the display screen.

[0034] The present invention has the following beneficial effects compared with the prior art:

[0035] The present invention provides a method for testing the DC resistance of a winding without disassembling the lead wires of a converter transformer. The test voltage and current are provided by a measuring device to test the tubular busbar and the converter transformer windings, and the defects of the grid-side valve-side windings are judged and evaluated. The test method without disassembling the lead wires greatly reduces the maintenance cycle, reduces the maintenance cost, avoids the risk of safety maintenance, facilitates testing, and improves the test efficiency. The lean maintenance of converter transformers in UHV converter stations and hub substations and the reliability of equipment are greatly improved, and the maintenance cycle, maintenance cost, safety maintenance risk and poor emergency measures can be greatly reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0037] Figure 1 A flow chart of a method for measuring the DC resistance of a commutation transformer winding without disassembling a tubular busbar proposed by the present invention;

[0038] Figure 2 The wiring diagram of the measuring device proposed by the present invention;

[0039] Figure 3 This is a structural diagram of a device for measuring the DC resistance of a commutation transformer winding without disassembling a tubular busbar, as proposed by the present invention;

[0040] Figure 4 This is a control structure diagram of a device for measuring the DC resistance of a tubular busbar commutation transformer winding without disassembling the commutation transformer winding, as proposed by the present invention. DETAILED DESCRIPTION

[0041] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. It should be understood that the specific embodiments described are only used to explain the present application and are not used to limit the present application.

[0042] Lean maintenance of converter stations and improvement of reliability of electrical equipment are crucial to the safe and stable operation of power systems. Optimizing maintenance arrangements, innovating test methods, and streamlining test personnel have significant effects on reducing power outage time and improving DC energy utilization. The method proposed in the present invention can greatly reduce maintenance cycles, reduce maintenance costs, and avoid maintenance safety risks, which is of great significance to the improvement of the operation and maintenance management capabilities of converter stations.

[0043] See also Figure 1 The present invention provides a method for measuring the DC resistance of a converter transformer winding without disassembling a tubular busbar, comprising:

[0044] Step 101, remove the flexible wires between the converter transformer busbar and the overhead line and the grounding copper bar; separate the grounding knife switch on the valve side of the converter transformer;

[0045] Step 102, connecting the measuring device to the tubular busbar and the commutation transformer winding;

[0046] Step 103, connecting the three-phase grid-side mother pipes respectively through a measuring device, measuring and calculating the grid-side and valve-side resistances of each phase winding;

[0047] Step 104 , evaluating the defects of the grid-side valve-side winding according to the calculated value and ratio of the grid-side valve-side resistance.

[0048] The present invention provides a method for testing the DC resistance of a winding without disassembling the leads of a converter transformer. The method provides a test voltage and current through a measuring device, tests the tubular bus and the converter transformer winding, and judges and evaluates the defects of the grid-side valve-side winding. The test method without disassembling the leads greatly reduces the maintenance cycle, reduces the maintenance cost, avoids the risk of safety maintenance, facilitates testing, and improves the test efficiency.

[0049] The specific test process of the present invention is to first remove the soft wires between the converter transformer tube busbar and the overhead line and the grounding copper busbar, and then separate the grounding knife switch; next, perform test wiring, connect the test device to the pipeline busbar and the converter transformer winding, and after the connection is completed, perform the test and display the test results. According to the test results, the winding defects on the grid side or the valve side are judged to complete the test evaluation.

[0050] See also Figure 2 In step 102, the measuring device is connected to the tubular busbar and the converter transformer winding; specifically comprising:

[0051] Carry out wiring according to the wiring diagram. One end of the current excitation harness is connected to the tubular busbar, and the other end is connected to the current interface of the measuring host. One end of the voltage response harness is connected to the soft connection closest to the transformer winding terminal, and the other end is connected to the voltage interface of the measuring host. The jaws of the current measuring clamp are clamped on the neutral point soft connection on the grid side of the test transformer.

[0052] In step 103, the three-phase grid-side mother pipes are connected respectively by a measuring device to measure and calculate the grid-side and valve-side resistances of each phase winding; specifically, the steps include:

[0053] The measuring device provides DC excitation to test the grid-side voltage, valve-side voltage, and loop current, completing the grid-side voltage U L , valve side voltage U V The current measuring clamp completes the measurement of the loop current I; the measuring device completes the calculation of the single-phase DC resistance R of the grid-side winding L =U L / I, complete the calculation of the phase-to-phase DC resistance of the valve side winding R v =U v / I, complete the calculation of the resistance ratio of the network side to the valve side d = R L / R v .

[0054] In step 104, the grid-side valve-side winding defect is evaluated according to the grid-side valve-side resistance reduction value and ratio; specifically, the process includes:

[0055] Calculate the initial value difference of the single-phase DC resistance of the grid-side winding. When the initial value difference of the single-phase DC resistance of the grid-side winding is greater than the first set value, it is judged that the grid-side winding has poor contact; when the initial value difference of the single-phase DC resistance of the grid-side winding is less than the second set value, it is judged that the grid-side winding has an inter-turn short circuit.

[0056] The initial value difference of the single-phase DC resistance of the valve side winding is calculated. When the initial value difference of the single-phase DC resistance of the valve side winding is greater than the third set value, it is judged that the valve side winding has poor contact; when the initial value difference of the single-phase DC resistance of the valve side winding is less than the fourth set value, it is judged that the valve side winding has a short circuit between turns.

[0057] In the embodiment of the present invention, the initial value difference of the single-phase DC resistance of the grid-side winding is calculated as follows:

[0058] Grid-side winding single-phase DC resistance R L Initial value difference ΔR L Evaluation of R L Calculate from the test temperature to 75°C using R L(75)Compared with the factory test results R L(o) Make a comparison;

[0059]

[0060] The initial value difference of the single-phase DC resistance of the valve-side winding is calculated as follows:

[0061] Single-phase DC resistance of valve side winding R V Initial value difference ΔR v Evaluation, R V Calculate from the test temperature to 75°C using R V(75) Compared with the factory test results R V(o) Make a comparison;

[0062]

[0063] The first setting value is 2%, the second setting value is -2%, the third setting value is 1%, and the fourth setting value is -1%. See Table 1 and Table 2 for details:

[0064] Table 1

[0065] Defect Name <![CDATA[ΔR L (Warning value)]]> The grid side winding has poor contact ≥2％ Grid-side winding turn-to-turn short circuit ≤-2％

[0066] Table 2

[0067] Defect Name <![CDATA[ΔR V (Warning value)]]> The valve side winding has poor contact ≥1％ Short circuit between turns of valve side winding ≤-1％

[0068] In the embodiment of the present invention, the evaluation result is verified by the network side valve side resistance ratio; specifically, the evaluation of the network side valve side resistance ratio d initial value difference Δd is used to compare d with the factory test result d (o) Make a comparison;

[0069]

[0070] When Δd≥2%, it indicates poor contact of the grid-side winding; when Δd≤-2%, it indicates short circuit between turns of the grid-side winding;

[0071] When Δd≤-1%, the valve side winding has poor contact; when Δd≥1%, the valve side winding has short circuit between turns. See Table 3:

[0072] Table 3

[0073] Defect Name d Initial value difference (warning value) The grid side winding has poor contact ≥2％ Grid-side winding turn-to-turn short circuit ≤-2％ The valve side winding has poor contact ≤-1％ Short circuit between turns of valve side winding ≥1％

[0074] In the embodiment of the present invention, the jaws of the current measuring clamp are clamped on the soft connection at the center point of the test converter transformer grid side, and are closer to the winding terminal than the connection point of the voltage response harness. The current test clamp is set on the winding terminal side, and the measurement result is closer to the true value of the grid side winding or the valve side winding, which can effectively avoid the inaccurate measurement caused by shunting and voltage division at the rear end of the voltage response harness.

[0075] Taking a converter station as an example, actual measurements were carried out at a converter station, using traditional measurement methods and the method described in this document. In terms of on-site construction, the traditional measurement method requires the removal of the grid-side mother tube and valve-side mother tube of each (group) transformer. On average, each transformer needs to remove 2 mother tubes and disconnect 6 leads; the method described in this article does not require the removal of the mother tube, and on average, each transformer disconnects 1 lead. In terms of test effect: the initial value difference of the grid-valve resistance ratio of a certain phase transformer reaches -1.53%, and the initial value difference of the valve-side resistance reaches 1.74%. According to the defect judgment matrix shown in the table, the transformer valve-side winding has a poor contact defect; under the traditional test method, the initial value difference of the valve-side resistance is 2.03%, and the transformer valve-side winding has a poor contact defect. See Table 4 for the test results of the measurement method of the DC resistance of the converter transformer winding without disassembling the tubular busbar of the present invention, and Table 5 for the measurement results of the traditional test method. By comparison, it can be seen that the method described in this article is equivalent to the traditional measurement method, but it can avoid the workload of disassembling the tubular busbar and significantly reduce the number of disconnections.

[0076] Table 4

[0077]

[0078] Table 5

[0079]

[0080] See also Figure 3 and Figure 4 The present invention also provides a device for measuring the DC resistance of a converter transformer winding without disassembling a tubular busbar, comprising:

[0081] A shell 200, wherein a current excitation module, a current measurement module, a voltage measurement module, and a controller are arranged inside the shell; an operation panel is arranged on the shell, and a current excitation terminal 201, a voltage response terminal 203, a current measurement clamp interface 202, a display screen 204, and a current transition harness 205 are arranged on the operation panel, wherein the current excitation terminal is connected to the output end of the current excitation module, the voltage measurement module is connected to the voltage response terminal, and the current measurement clamp interface is connected to the current measurement module; the current excitation module, the current measurement module, and the voltage measurement module are connected to the controller; and the output end of the controller is connected to the display screen.

[0082] The various variations and specific examples of the methods in the aforementioned embodiments are also applicable to a device for measuring the DC resistance of a tubular busbar without disassembling a commutator transformer winding in this embodiment. Through the aforementioned detailed description of the method for measuring the DC resistance of a tubular busbar without disassembling a commutator transformer winding, those skilled in the art can clearly know the device for measuring the DC resistance of a tubular busbar without disassembling a commutator transformer winding in this embodiment. Therefore, for the sake of brevity of the specification, it will not be described in detail here.

[0083] The present invention is described in detail above, but the present invention is not limited to the above-mentioned embodiments. Various changes can be made within the knowledge of ordinary technicians in the field without departing from the purpose of the present invention. Many other changes and modifications can be made without departing from the concept and scope of the present invention. It should be understood that the present invention is not limited to specific embodiments, and the scope of the present invention is defined by the appended claims.

Claims

1. A method for measuring the DC resistance of a converter transformer winding without disassembling a tubular busbar, characterized in that: include: Remove the flexible conductors between the converter transformer busbar and the overhead line and grounding copper busbar; Separate the grounding switch on the valve side of the converter transformer; Connect the measuring device to the tubular busbar and the commutation transformer winding; The three-phase grid-side pipe mother is connected to measure the DC resistance of each phase winding through the measuring device, and the grid-side valve-side resistance conversion value and ratio are calculated; Evaluate the defects of the grid-side valve-side windings based on the calculated value and ratio of the grid-side valve-side resistance; The method of connecting the measuring device to the tubular busbar and the converter transformer winding specifically includes: Carry out wiring according to the wiring diagram. One end of the current excitation harness is connected to the tubular busbar, and the other end is connected to the current interface of the measuring host. One end of the voltage response harness is connected to the soft connection closest to the transformer winding terminal, and the other end is connected to the voltage interface of the measuring host. The jaws of the current measuring clamp are clamped on the neutral point soft connection on the test transformer grid side. The measuring device is connected to the three-phase grid-side pipe mother to measure the DC resistance of each phase winding, and calculate the grid-side valve-side resistance reduction value and ratio; specifically includes: The measuring device provides DC excitation to test the grid-side voltage, valve-side voltage, and loop current, completing the grid-side voltage U L , valve side voltage U V The current measuring clamp completes the measurement of the loop current I; the measuring device completes the calculation of the single-phase DC resistance R of the grid-side winding L =U L / I, complete the calculation of the phase-to-phase DC resistance of the valve side winding R v =U v / I, complete the calculation of the resistance ratio of the network side to the valve side d = R L / R v .

2. The method for measuring the DC resistance of a converter transformer winding without disassembling a tubular busbar according to claim 1 is characterized in that: The evaluation of the grid-side valve-side winding defects according to the grid-side valve-side resistance reduction value and ratio specifically includes: Calculate the initial value difference of the single-phase DC resistance of the grid-side winding. When the initial value difference of the single-phase DC resistance of the grid-side winding is greater than the first set value, it is judged that the grid-side winding has poor contact; when the initial value difference of the single-phase DC resistance of the grid-side winding is less than the second set value, it is judged that the grid-side winding has an inter-turn short circuit. The initial value difference of the single-phase DC resistance of the valve side winding is calculated. When the initial value difference of the single-phase DC resistance of the valve side winding is greater than the third set value, it is judged that the valve side winding has poor contact; when the initial value difference of the single-phase DC resistance of the valve side winding is less than the fourth set value, it is judged that the valve side winding has a short circuit between turns.

3. The method for measuring the DC resistance of a converter transformer winding without disassembling a tubular busbar according to claim 2 is characterized in that: The initial value difference of the single-phase DC resistance of the grid-side winding is calculated as follows: Grid-side winding single-phase DC resistance R L Initial value difference ΔR L Evaluation of R L Calculate from the test temperature to 75°C using R L(75) Compared with the factory test results R L(o) Make a comparison; The initial value difference of the single-phase DC resistance of the valve-side winding is calculated as follows: Single-phase DC resistance of valve side winding R V Initial value difference ΔR v Evaluation, R V Calculate from the test temperature to 75°C using R V(75) Compared with the factory test results R V(o) Make a comparison; 4. The method for measuring the DC resistance of a converter transformer winding without disassembling a tubular busbar according to claim 2 is characterized in that: The first setting value is 2%, the second setting value is -2%, the third setting value is 1%, and the fourth setting value is -1%.

5. The method for measuring the DC resistance of a converter transformer winding without disassembling a tubular busbar according to claim 1 is characterized in that: Also includes: The evaluation results are verified by comparing the grid-side and valve-side resistances; specifically: Evaluation of the difference Δd between the initial value of the resistance ratio d on the grid side and the valve side, using d and the factory test result d (o) Make a comparison; When Δd≥2%, it indicates poor contact of the grid-side winding; when Δd≤-2%, it indicates short circuit between turns of the grid-side winding; When Δd≤-1%, the valve side winding has poor contact; when Δd≥1%, the valve side winding has a short circuit between turns.

6. The method for measuring the DC resistance of a converter transformer winding without disassembling a tubular busbar according to claim 1 is characterized in that: The jaws of the current measuring clamp are clamped on the soft connection at the center point of the test commutation transformer grid side and are closer to the winding terminal than the connection point of the voltage response harness.

7. A device for measuring the DC resistance of a converter transformer winding without disassembling a tubular busbar, characterized in that: A method for measuring the DC resistance of a converter transformer winding without disassembling a tubular bus as claimed in any one of claims 1 to 6 comprises: A shell, wherein a current excitation module, a current measurement module, a voltage measurement module, and a controller are arranged inside the shell; an operation panel is arranged on the shell, and a current excitation terminal, a voltage response terminal, a current measurement clamp interface, and a display screen are arranged on the operation panel, the current excitation terminal is connected to the output end of the current excitation module, the voltage measurement module is connected to the voltage response terminal, and the current measurement clamp interface is connected to the current measurement module; the current excitation module, the current measurement module, and the voltage measurement module are connected to the controller; and the output end of the controller is connected to the display screen.

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