An equivalent simulation method for determining pressure distribution of current transformer oil conservator

Abstract

This invention discloses an equivalent simulation method for determining the pressure distribution of an oil-immersed current transformer's oil conservator, comprising: preparing an experimental enclosure that can accommodate the oil-immersed current transformer; fixing the oil-immersed current transformer at the center of the experimental enclosure; establishing a coordinate system for the position of the oil-immersed current transformer within the experimental enclosure; determining a fault point coordinate and a determined pressure distribution coordinate on the oil conservator enclosure of the oil-immersed current transformer; setting a pressure sensor at the determined pressure distribution coordinate point; placing the arc generator head of a short-circuit impulse generator at the determined fault point coordinate; filling the experimental enclosure with insulating oil; adjusting the magnitude of the arc energy released by the short-circuit impulse generator; obtaining the pressure signal corresponding to the arc energy magnitude from the pressure sensor; and calculating the actual pressure values ​​borne by the oil conservator enclosure of the current transformer at the pressure distribution points corresponding to different energy magnitudes.

Description

Technical Field

[0001] This invention relates to an equivalent simulation method for determining the pressure distribution of a current transformer oil tank. Background Technology

[0002] Statistics show that in the past five years, eight faults and 39 serious and critical defects have occurred in inverted current transformers at voltage levels of 220kV and above in the Jiangsu power grid. The highest failure rate was observed at the head of the inverted oil-immersed current transformer. Explosions are common in accidents caused by inverted oil-immersed current transformers. These accidents not only reduce the transmitted power but also damage other nearby equipment in the substation, posing a significant threat to the safety and reliability of the power grid. The root cause of the explosion is an internal arc fault leading to the rapid expansion of the oil-gas mixture, which in turn causes the oil conservator to rupture due to excessive pressure. Due to the complex internal structure of the transformer and the rapid development of arc faults, the oil-gas conversion process and its distribution, as well as the diffusion law of the oil-gas mixture, are currently unclear. Therefore, research on the internal arc faults of inverted oil-immersed current transformers is particularly important.

[0003] Currently, when using a physical current transformer to conduct pressure distribution tests on oil conservator tanks, the experiments can only be performed within the elastic limits of the tank. When the energy released by an arc fault exceeds a certain value, the tank will rupture, making it impossible to conduct further pressure release tests on larger arc fault energies. Furthermore, using a physical current transformer for pressure distribution tests on oil conservator tanks is cumbersome, carries a high risk factor, and results in significant material waste. Therefore, there is an urgent need for a method that can simulate the pressure distribution of the current transformer in the oil conservator tank under overload arc fault energy without damaging the current transformer. Summary of the Invention

[0004] The purpose of this invention is to propose an equivalent simulation method for determining the pressure distribution of the current transformer oil tank, which can ensure that the pressure distribution of the current transformer oil tank under overload arc fault energy is simulated without damaging the current transformer oil tank.

[0005] To achieve the above objectives, the technical solution of the present invention is as follows:

[0006] An equivalent simulation method for determining the pressure distribution of a current transformer oil conservator includes:

[0007] Step 1: Prepare a cube-shaped experimental box that can accommodate the oil-immersed current transformer. Fix the oil-immersed current transformer at the center of the cube-shaped experimental box and establish the position coordinate system of the oil-immersed current transformer in the cube-shaped experimental box.

[0008] Step 2: Determine an arc breakdown fault point on the oil tank of the oil-immersed current transformer, and determine the pressure distribution point on the oil tank relative to the arc breakdown fault point, thus forming the fault point coordinates and the pressure distribution coordinates in the coordinate system.

[0009] Step 3: Remove the oil tank of the oil-immersed current transformer and take it out. Set up a pressure sensor at the determined pressure distribution coordinate point and place the arc generating head of the short-circuit impact generator at the determined fault point coordinate point.

[0010] Step 4: Fill the cube-shaped experimental chamber with insulating oil, adjust the magnitude of the arc energy released by the short-circuit impact generator, obtain the pressure signal corresponding to the arc energy magnitude from the pressure sensor, and calculate the actual pressure value borne by the oil conservator of the current transformer at the pressure distribution point corresponding to different energy magnitudes using Formula 1:

[0011] Formula 1

[0012] in:

[0013] F i The actual pressure value that the transformer oil tank body bears at the pressure distribution point;

[0014] β is the coefficient of thermal volume expansion of the insulating oil;

[0015] E represents the magnitude of the electric arc energy released by the short-circuit impact generator;

[0016] n is the ratio of the volume of the cube-shaped experimental chamber to the volume of the current transformer oil tank chamber;

[0017] Fni is the pressure value of the pressure sensor at the pressure distribution point location;

[0018] v is the kinematic viscosity of the insulating oil;

[0019] Li is the distance between the pressure distribution point and the arc breakdown fault point;

[0020] V is the volume of insulating oil in the current transformer.

[0021] A further provision of the scheme is that the volume of the cube-shaped experimental chamber is at least three times the volume of the oil-immersed current transformer.

[0022] A further step in the solution is that the pressure sensor and the arc generator are positioned at the pressure distribution coordinate point and the fault point coordinate point by a support fixed on the side wall of the cubic experimental chamber.

[0023] A further aspect of the solution is that the distribution point of the maximum pressure bearing capacity of the oil tank is the cross-sectional point of the oil tank body horizontally surrounding the fault point on the same plane as the fault point, and the cross-section is perpendicular to the primary conductor rod of the current transformer.

[0024] The beneficial effects of this invention are as follows: This invention simulates the pressure distribution of the current transformer's oil conservator by placing the oil-immersed current transformer in a simulated enclosure. Using the arc fault point as the origin of the short-circuit impact generator arc release, the pressure signal of the oil-immersed current transformer enclosure relative to the arc release origin is obtained through sensor testing. The experimental data obtained from the simulation is then detected and converted using an equivalent calculation method to obtain the pressure condition of the current transformer's oil conservator under overload arc fault energy, and thus the pressure distribution of the oil conservator under overload arc fault energy. This invention ensures that the pressure distribution of the current transformer's oil conservator under overload arc fault energy can be simulated without damaging the current transformer's oil conservator.

[0025] The present invention will now be described in detail with reference to the accompanying drawings and embodiments. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the structure of the simulation device of the present invention;

[0027] Figure 2 This is a schematic diagram of the test setup for the maximum pressure distribution point of the present invention. Detailed Implementation

[0028] An equivalent simulation method for determining the pressure distribution of a current transformer oil tank, using simulation equipment such as... Figure 1 As shown, the method includes:

[0029] Step 1: Prepare a cube-shaped experimental box 2 that can accommodate the oil-immersed current transformer 1. To facilitate operation and reduce simulation errors, the volume of the cube-shaped experimental box 2 should be at least three times the volume of the oil-immersed current transformer. The oil-immersed current transformer 1 includes an oil tank and primary and secondary coil conductors. Fix the oil-immersed current transformer 1 at the center of the cube-shaped experimental box and establish the position coordinate system of the oil-immersed current transformer in the cube-shaped experimental box by measurement.

[0030] Step 2: Determine an arc breakdown fault point or arc breakdown source 101 on or inside the oil conservator of the oil-immersed current transformer 1, determine a pressure distribution point 102 relative to the arc breakdown fault point on the oil conservator, and form the fault point coordinates and the pressure distribution coordinates in the coordinate system based on the coordinate system.

[0031] Step 3: Remove the oil tank of the oil-immersed current transformer and take it out. Set the pressure sensor 103 at the determined pressure distribution coordinate point by fixing the support (e.g., welded lead wire, not shown in the figure) on the side wall of the cube test box. The pressure sensor signal is connected to the analysis and test processor 4. Place the arc generating head 301 of the short-circuit impact generator 3 (existing equipment) at the determined fault point coordinate point.

[0032] Step 4: Fill the cube-shaped experimental chamber with insulating oil, adjust the magnitude of the arc energy released by the short-circuit impact generator, obtain the pressure signal corresponding to the arc energy magnitude from the pressure sensor, and calculate the actual pressure value borne by the oil conservator of the current transformer at the pressure distribution point corresponding to different energy magnitudes using Formula 1:

[0033] Formula 1

[0034] in:

[0035] F i The actual pressure value that the transformer oil tank body bears at the pressure distribution point;

[0036] β is the coefficient of thermal volume expansion of the insulating oil;

[0037] E represents the magnitude of the electric arc energy released by the short-circuit impact generator;

[0038] n is the ratio of the volume of the cube-shaped experimental chamber to the volume of the current transformer oil tank chamber;

[0039] Fni is the pressure value of the pressure sensor at the pressure distribution point location;

[0040] v is the kinematic viscosity of the insulating oil;

[0041] Li is the distance between the pressure distribution point and the arc breakdown fault point;

[0042] V is the volume of insulating oil in the current transformer.

[0043] According to the formula, the distribution point of the maximum pressure of the oil tank body can be determined to be the cross-sectional point of the oil tank body horizontally surrounding the fault point on the same plane as the fault point, and the cross-section is perpendicular to the primary conductor rod 4 of the current transformer, and the secondary coil 5 is surrounding the primary conductor rod 4.

[0044] Figure 2 This illustration shows a specific implementation example of measuring the maximum value of 12 distribution points on the pressure bearing capacity of an oil tank, such as... Figure 2As shown, the arc fault occurrence point 101 is recorded as the center point. Twelve dividing lines are drawn, each 30°, and each line intersects the inner surface of the current transformer oil tank at twelve points. These intersections are the pressure distribution points 102. The horizontal intersection at 0° is a1, and the clockwise intersections are a2...a12. These twelve intersections are used as pressure acquisition points, and the coordinates of each intersection relative to the center 101 are recorded. The current transformer oil tank and its components below are removed. Twelve pressure sensors 103 are arranged sequentially inside the cube-shaped experimental chamber to collect pressure signals based on the coordinates of the pressure acquisition points. The cube-shaped experimental chamber is filled with insulating oil. The magnitude of the arc energy released by the short-circuit impact generator is set, and the maximum value of the pressure signals collected by the twelve pressure sensors is recorded. The actual pressure value at the corresponding location of the current transformer oil tank can be calculated using Formula 1.

[0045] Through the above-described embodiment of the equivalent simulation method for the pressure distribution of the oil tank under arc fault in an oil-immersed current transformer, a simulation experiment is conducted on the pressure distribution of the oil tank of the current transformer. By using the equivalent calculation method, the experimental data obtained from the simulation experiment is detected and converted, so that the pressure condition of the oil tank of the current transformer under the overload arc fault energy can be obtained without damaging the oil tank of the current transformer.

Claims

1. An equivalent simulation method for determining the pressure distribution of a current transformer oil tank, characterized in that, The method includes: Step 1: Prepare a cube-shaped experimental box that can accommodate the oil-immersed current transformer. Fix the oil-immersed current transformer at the center of the cube-shaped experimental box and establish the position coordinate system of the oil-immersed current transformer in the cube-shaped experimental box. Step 2: Determine an arc breakdown fault point on the oil tank of the oil-immersed current transformer, and determine the pressure distribution point on the oil tank relative to the arc breakdown fault point, thus forming the fault point coordinates and the pressure distribution coordinates in the coordinate system. Step 3: Remove the oil tank of the oil-immersed current transformer and take it out. Set up a pressure sensor at the determined pressure distribution coordinate point and place the arc generating head of the short-circuit impact generator at the determined fault point coordinate point. Step 4: Fill the cube-shaped experimental chamber with insulating oil, adjust the magnitude of the arc energy released by the short-circuit impact generator, obtain the pressure signal corresponding to the arc energy magnitude from the pressure sensor, and calculate the actual pressure value borne by the oil conservator of the current transformer at the pressure distribution point corresponding to different energy magnitudes using Formula 1: Formula 1 in: F i The actual pressure value that the transformer oil tank body bears at the pressure distribution point; β is the coefficient of thermal volume expansion of the insulating oil; E represents the magnitude of the electric arc energy released by the short-circuit impact generator; n is the ratio of the volume of the cube-shaped experimental chamber to the volume of the current transformer oil tank chamber; Fni is the pressure value of the pressure sensor at the pressure distribution point location; v is the kinematic viscosity of the insulating oil; Li is the distance between the pressure distribution point and the arc breakdown fault point; V is the volume of insulating oil in the current transformer.

2. The equivalent simulation method according to claim 1, characterized in that, The volume of the cube-shaped experimental chamber is at least three times the volume of the oil-immersed current transformer.

3. The equivalent simulation method according to claim 1, characterized in that, The pressure sensor and the arc generator are positioned at the pressure distribution coordinate point and the fault point coordinate point by a support fixed on the side wall of the cubic experimental chamber.

4. The equivalent simulation method according to claim 1, characterized in that, The distribution point of the maximum pressure bearing capacity of the oil tank is the cross-sectional point of the oil tank body horizontally surrounding the fault point on the same plane as the fault point, and the cross-section is perpendicular to the primary conductor rod of the current transformer.

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