CN103149506A - Power transformer interturn insulation surface bubble partial discharge simulation experimental platform and experimental method - Google Patents

Abstract

The invention relates to an experimental platform and an experimental method for simulating partial discharge of air bubbles on the inter-turn insulation surface of a power transformer, belonging to the technical field of electric power technology equipment. The experimental platform includes power frequency test transformers, partial discharge testers, test products, etc. The test products: one section of the two test winding models is connected to the wire, and the two windings are respectively used as the high-voltage end and the low-voltage end. On both sides, diagonally outgoing wires, arranged side by side with the test transformer windings and fixed by connecting straps, placed on the insulating cardboard used to support the test sample, and placed in a glass cylinder container filled with insulating oil. Vacuumize and inject oil into the test device, calibrate the source setting signal; inject 10-50 air bubbles respectively, and measure the partial discharge corresponding to the gradually increasing voltage of the power frequency voltage. The present invention designs this experiment platform according to the power transformer operated on site, and mainly studies the influence of the size and quantity of air bubbles on partial discharge of inter-turn insulation. It provides a way to study the partial discharge characteristics of suspended bubbles in transformer oil.

Description

Partial discharge simulation experiment platform and experimental method of air bubbles on the inter-turn insulation surface of power transformers

technical field

The invention relates to an experimental platform and an experimental method for simulating partial discharge of air bubbles on the inter-turn insulation surface of a power transformer, which belong to the technical field of electric power technology equipment.

Background technique

Today, with the rapid development of my country's power system scale, the requirements for the operation safety and reliability of the entire power system are getting higher and higher. The power transformer is one of the essential electrical equipment in the power system, and its safe, stable and normal operation must be guaranteed. The occurrence of partial discharge in equipment is one of the important reasons that threaten the safe operation of equipment. Partial discharge refers to the electrical discharge phenomenon in which a local area of the insulating medium is broken down under a certain electric field. The inhomogeneity of the insulation strength in certain areas inside or on the surface of the insulating medium causes serious distortion of the electric field in this area, and the electric field strength is higher than the average electric field intensity. Therefore, in such an area, discharge will occur first, while other areas still maintain insulating properties. , which forms a partial discharge. Partial discharge is not only an important cause of insulation degradation of power transformers, but also an important symptom of its occurrence. Gas is one of the most important factors affecting partial discharge.

In the process of installation, oil filling and maintenance of the oil-immersed power transformer in operation, a certain amount of gas will inevitably enter, which will reduce the insulation performance of the oil-paper. Since the air bubbles in the transformer oil will always maintain a state of suspension and movement in the transformer box, when the air bubbles in the oil pass through the strong electric field area, it will inevitably cause partial discharge, which will further deteriorate the oil-paper insulation and generate more Harmful gases will accelerate the degradation of the insulation performance of the equipment, and in severe cases, it will cause insulation breakdown of the equipment. At present, there are a lot of studies on the discharge characteristics of air gap defects at home and abroad, but there are few studies on the partial discharge characteristics of suspended bubbles, especially the research on the deformation mechanism of bubbles and the factors affecting bubble discharge have not been reported. Therefore, it has certain theoretical value and practical significance to study the partial discharge characteristics and fault diagnosis of inter-turn insulation surface bubbles in transformer oil.

Contents of the invention

Purpose of the invention: when there are suspended air bubbles in the transformer oil, the suspended air bubbles will cause partial discharge under certain conditions and affect the normal operation of the power transformer. The present invention is based on the partial discharge detection of transformers at home and abroad, and according to the real situation of suspended bubbles in the transformer oil on site, this platform uses the experimental device in the laboratory to simulate the partial discharge of suspended bubbles in the transformer oil, and analyzes the suspended bubbles in the oil. The discharge mechanism of moving bubbles and the partial discharge signal of suspended bubbles in oil were obtained through experiments for analysis.

A partial discharge simulation experiment platform for air bubbles on the inter-turn insulation surface of a power transformer, which includes an AC-high voltage power supply; LDS-6 digital partial discharge tester, T1---HY-AC20-1 electric voltage regulator, T2 ---YDT-5/50 power frequency test transformer, C---800PF coupling capacitor, etc., Cx---test product;

The electric voltage regulator (2) is connected with the AC-high voltage power supply (1) through wires, the power frequency test transformer (3) is connected with the electric voltage regulator (2) through wires, and the AC-high voltage power supply (1) supplies power, and the power frequency test The transformer (3) adjusts the voltage; the protective resistor (4) is connected with the power frequency test transformer (3) through the wire, and the protective resistor (4) is connected in parallel with the test object (7) and the coupling capacitor (5) through the wire; the partial discharge measuring instrument ( 6) Connect with the coupling capacitor (5) through wires;

The sample to be tested is as follows: one section of the two winding models for testing is connected to the wire, and is soldered with an electric soldering iron. , arranged side by side with the test transformer windings and fixed by connecting straps, placed on the insulating cardboard used to support the test sample, and placed in a glass cylinder container filled with insulating oil.

(The structure of the sample is shown in Figure 3)

The present invention also provides a method for simulating a partial discharge simulation experiment of air bubbles on the inter-turn insulation surface of a power transformer. The steps of the method are as follows:

(1) Vacuumize the test device and inject oil

In order to make the experiment closer to the real situation, this step is excluded because the winding or transformer oil contains gases that may affect the experimental results before the experiment is carried out.

Put the winding model in a glass container, pour transformer oil into the container so that the winding model is completely below the oil surface. Put the whole device in a vacuum drying oven to evacuate for 12 hours, then set the temperature to 80 degrees and inject oil for 48 hours, take it out, and seal the container mouth with plastic wrap to prevent the water in the air from dissolving in the oil. Waiting to experiment.

(2) Calibrate the experiment before the experiment starts, the calibration source sets the signal to 20pc, and the PD instrument to be observed shows that the signal is 20pc, and the experiment can be started. Connect one section of the two test winding models to the wires respectively, and solder them firmly with an electric soldering iron until they fall off during the test. The two windings are respectively used as the high-voltage end and the low-voltage end, and are placed on both sides of the five windings, diagonally The outlet wires are arranged side by side with the test transformer windings and fixed by connecting straps, and placed on the insulating cardboard used to support the test object, as shown in Figure 3.

Before the experiment, a tentative test was carried out, mainly to inject air bubbles into the inter-turns of the experimental winding, because the air bubbles are injected by a syringe, and are easy to fix between the turns, and repeated injections are required before each experiment to obtain the expected effect.

(3) Start to inject air bubbles and perform partial discharge test: before injecting air bubbles, measure the voltage at which partial discharge occurs when there are no air bubbles, and record several voltage measurements.

(4) Inject two bubbles three times, with different volumes of bubbles. Measure the partial discharge corresponding to the voltage when the power frequency voltage gradually increases. The volumes of the bubbles are 0.015ml, 0.06ml and 0.15ml respectively. (The volume is an estimate. The method is to insert the syringe into the oil and inject it smoothly. It is obtained from the scale difference/the number of output gases. The volume of each bubble is about 0.015ml, and the bubbles fuse with each other to obtain larger volume bubbles) .

(5) Inject about 10, 30, and 50 bubbles respectively, and measure the partial discharge corresponding to the gradually increasing voltage of the power frequency voltage.

According to the suspended air bubbles in the power transformer oil in the field and the characteristics of the internal structure of the transformer, this experimental platform designs a partial discharge simulation experiment device for suspended air bubbles in the oil. Impact. Provide an experimental platform for the study of partial discharge characteristics of suspended bubbles in transformer oil.

this invention:

(1) Analog transformer winding design

There are many structural types of transformer windings. According to the different requirements for the insulation strength and electric field strength of the transformer itself, four main structural types are usually used: layer type, entangled type, spiral type and barrel type. This platform cuts the transformer winding into five sections of 15cm, welds two ends of each of them to the wire with a soldering iron, and wraps them with transparent tape. Wrap the part of the copper rod that is not connected to the wire with a transparent adhesive tape and extend it by 2cm to extend the possible partial discharge distance and isolate the occurrence of inter-turn discharge. Fix the five windings together with fastening straps and place them on a support platform made of insulating cardboard in a glass container (model shown in Figure 3).

(2) Suspended bubble artificial model

In order to truly simulate the suspended air bubbles in the oil, the whole device is first filled with transformer oil. In order to analyze the partial discharge characteristics of the air bubbles on the inter-turn insulation surface in the oil, this paper uses the static air bubbles in the oil as a reference for research. Therefore, a small-capacity syringe is used to inject air bubbles into the gaps of the windings in the simulation device respectively. In order to make the defects that promote partial discharge occur due to the existence of air bubbles in the experimental device, it is convenient for the observation of the experiment.

(3) Partial discharge detection system and instrument introduction

Wiring diagram of transformer partial discharge measurement system (as shown in Figure 1). LDS-6 digital partial discharge tester: it can directly collect and store the data to be measured.

HY-AC20 power frequency high voltage experimental console is composed of imported high-quality silicon steel sheet ring iron core, equipped with voltmeter and ammeter to monitor the operation status of electrical equipment in real time.

YDT-5/50 Power Frequency Test Transformer: It is suitable for power frequency AC voltage withstand test for electric power departments, large factories and mines, and electric power equipment (such as power transformers, switchgear, capacitors, transformers, etc.) with a voltage level of 220kV and below for scientific research , Partial discharge test of various electrical equipment (such as cables, large transformers, transformers, GIS combined electrical appliances, etc.).

According to the suspended air bubbles in the power transformer oil in the field and the characteristics of the internal structure of the transformer, the experimental platform designed a partial discharge simulation experiment device for suspended air bubbles in the oil. Influence. Provide an experimental platform for the study of partial discharge characteristics of suspended bubbles in transformer oil.

Description of drawings

Figure 1 Test circuit connection diagram. Among them, AC-high voltage power supply; LDS-6 digital partial discharge tester, T1---HY-AC20-1 type electric voltage regulator, T2---YDT-5/50 power frequency test transformer, C--- 800PF coupling capacitor, etc., Cx---test product.

Figure 2 is a schematic diagram of the DZ-3BC model vacuum drying oven used for the test.

Figure 3 is a schematic diagram of the sample.

Figure 4 is a structural diagram of the experimental platform

Detailed ways

Further illustrate the present invention below in conjunction with accompanying drawing.

Figure 1 is a connection diagram of the test circuit. Figure 2 is a schematic diagram of a vacuum drying oven for testing. Figure 3 is a schematic diagram of the sample. As shown in the figure, a partial discharge simulation experiment platform for air bubbles on the inter-turn insulation surface of a power transformer is characterized in that the experiment platform includes an AC-high voltage power supply (1), an electric voltage regulator (2), and a power frequency test transformer (3 ), protective resistor (4), coupling capacitor (5), partial discharge tester (6), test product (7); electric voltage regulator (2) and AC-high voltage power supply (1) are connected by wires, power frequency test The transformer (3) is connected to the electric voltage regulator (2) through wires, the AC-high voltage power supply (1) supplies power, and the power frequency test transformer (3) adjusts the voltage; the protection resistor (4) is connected to the power frequency test transformer (3) through wires connection, the protective resistor (4) is connected in parallel with the test object (7) and the coupling capacitor (5) through the wire; the partial discharge measuring instrument (6) is connected with the coupling capacitor (5) through the wire; the test object is: two One section of the winding model is connected to the wire and soldered with an electric soldering iron. The two windings are used as the high-voltage end and the low-voltage end respectively, and are placed on both sides of the five windings. The connection strap is fixed, placed on the insulating cardboard used to support the test object, and placed in a glass cylinder container filled with insulating oil. The electric voltage regulator is HY-AC20-1 type electric voltage regulator.

The power frequency test transformer is YDT-5/50 power frequency test transformer.

The partial discharge tester is an LDS-6 digital partial discharge tester.

The coupling capacitance is 800PF.

Using this power transformer turn-to-turn insulation surface bubble partial discharge simulation experiment method is as follows:

(1) Vacuumize the test device and inject oil

In order to make the experiment closer to the real situation, this step is excluded because the winding or transformer oil contains gases that may affect the experimental results before the experiment is carried out.

Put the winding model in a glass container, pour transformer oil into the container so that the winding model is completely below the oil surface. Put the whole device in a vacuum drying oven to evacuate for 12 hours, then set the temperature to 80 degrees and inject oil for 48 hours, take it out, and seal the container mouth with plastic wrap to prevent the water in the air from dissolving in the oil. Waiting to experiment.

(2) Calibrate the experiment before the experiment starts, the calibration source sets the signal to 20pc, and the PD instrument to be observed shows that the signal is 20pc, and the experiment can be started. Connect one section of the two test winding models to the wires respectively, and solder them firmly with an electric soldering iron until they fall off during the test. The two windings are respectively used as the high-voltage end and the low-voltage end, and are placed on both sides of the five windings, diagonally The outlet wires are arranged side by side with the test transformer windings and fixed by connecting straps, and placed on the insulating cardboard used to support the test object, as shown in Figure 3.

Before the experiment, a tentative test was carried out, mainly to inject air bubbles into the inter-turns of the experimental winding, because the air bubbles are injected by a syringe, and are easy to fix between the turns, and repeated injections are required before each experiment to obtain the expected effect.

(3) Start to inject air bubbles and perform partial discharge test: before injecting air bubbles, measure the voltage at which partial discharge occurs when there are no air bubbles, and record several voltage measurements.

(4) Inject two bubbles three times, with different volumes of bubbles. Measure the partial discharge corresponding to the voltage when the power frequency voltage gradually increases. The volumes of the bubbles are 0.015ml, 0.06ml and 0.15ml respectively. (The volume is an estimate. The method is to insert the syringe into the oil and inject it smoothly. It is obtained from the scale difference/the number of output gases. The volume of each bubble is about 0.015ml, and the bubbles fuse with each other to obtain larger volume bubbles) .

(5) Inject about 10, 30, and 50 bubbles respectively, and measure the partial discharge corresponding to the gradually increasing voltage of the power frequency voltage.

According to the suspended air bubbles in the power transformer oil operated on site and the characteristics of the internal structure of the transformer, the experimental platform of the present invention designs a partial discharge simulation experiment device for suspended air bubbles in the oil. The effect of discharge. Provide an experimental platform for the study of partial discharge characteristics of suspended bubbles in transformer oil.

Claims (6)

1. Power transformer turn-to-turn insulation surface bubble partial discharge simulation experiment platform, characterized in that the experiment platform includes AC-high voltage power supply (1), electric voltage regulator (2), power frequency test transformer (3), protection resistor ( 4), coupling capacitor (5), partial discharge tester (6), sample (7); The electric voltage regulator (2) is connected with the AC-high voltage power supply (1) through wires, the power frequency test transformer (3) is connected with the electric voltage regulator (2) through wires, and the AC-high voltage power supply (1) supplies power, and the power frequency test The transformer (3) adjusts the voltage; the protective resistor (4) is connected with the power frequency test transformer (3) through the wire, and the protective resistor (4) is connected in parallel with the test object (7) and the coupling capacitor (5) through the wire; the partial discharge measuring instrument ( 6) Connect with the coupling capacitor (5) through wires; The sample to be tested is as follows: one section of the two winding models for testing is connected to the wire, and is soldered with an electric soldering iron. , arranged side by side with the test transformer windings and fixed by connecting straps, placed on the insulating cardboard used to support the test sample, and placed in a glass cylinder container filled with insulating oil. 2. The simulation experiment platform for partial discharge of air bubbles on the inter-turn insulation surface of a power transformer according to claim 1, wherein the electric voltage regulator is a HY-AC20-1 type electric voltage regulator. 3. The power transformer turn-to-turn insulation surface bubble partial discharge simulation experiment platform according to claim 1, characterized in that, the power frequency test transformer is a YDT-5/50 power frequency test transformer. 4. The partial discharge simulation experiment platform for air bubbles on the inter-turn insulation surface of a power transformer according to claim 1, wherein the partial discharge tester is an LDS-6 digital partial discharge tester. 5 . The power transformer turn-to-turn insulation surface bubble partial discharge simulation experiment platform according to claim 1 , wherein the coupling capacitance is 800PF. 6. A method for simulating partial discharge of air bubbles on the inter-turn insulation surface of a power transformer, characterized in that the steps of the experiment method are: (1) Vacuumize the test device and inject oil Put the winding model in a glass container, inject transformer oil into the container so that the winding model is completely below the oil surface; put the whole device in a vacuum drying oven for 12 hours, then set the temperature to 80 degrees and fill the oil for 48 hours before taking it out. Seal the mouth of the container with plastic wrap to prevent the water in the air from dissolving in the oil; wait for the experiment; (2) Calibrate the experiment before the experiment starts. The signal of the calibration source is set to 20pc, and the signal displayed by the partial discharge instrument to be observed is 20pc. As the high-voltage end and the low-voltage end, it is placed on both sides of the five windings, and the diagonal line is out. It is arranged side by side with the test transformer winding and fixed by the connecting belt, and placed on the insulating cardboard used to support the test object; Before the experiment, a tentative test was carried out, mainly to inject air bubbles into the inter-turns of the experimental winding, because the air bubbles are injected by a syringe, and are easy to fix between the turns, and repeated injections are required before each experiment to obtain the expected effect; (3) Start to inject air bubbles and perform partial discharge test: before injecting air bubbles, measure the voltage at which partial discharge occurs when there are no air bubbles, and record several voltage measurements; (4) Inject two bubbles in three times. The volume of the bubbles is different. Measure the partial discharge volume corresponding to the voltage when the power frequency voltage gradually increases. The volumes of the bubbles are 0.015ml, 0.06ml and 0.15ml respectively; The method is to insert the syringe into the oil and inject it stably. According to the scale difference/number of output gases, the volume of each bubble is about 0.015ml, and the bubbles fuse with each other to obtain larger bubbles; (5) Inject about 10, 30, and 50 bubbles respectively, and measure the partial discharge corresponding to the gradually increasing voltage of the power frequency voltage.

Images