CN110662411A - A kind of electric power equipment with self-recovery insulation performance and using method thereof - Google Patents

Abstract

The invention relates to electric power equipment with self-recovery insulating property and a using method thereof, and solves the problems that the insulation cannot be recovered after the existing epoxy resin serving as an insulating medium of the electric power equipment is punctured, the epoxy resin needs to be replaced, and the whole equipment is damaged or even scrapped due to great replacing difficulty. The power electrical equipment comprises a shell and a plurality of electrical elements arranged in the shell; paraffin is arranged among the plurality of electric elements and between the electric elements and the shell, and the breakdown strength of the paraffin is greater than the field strength among the electric elements.

Description

A kind of electric power equipment with self-recovery insulation performance and using method thereof

technical field

The invention belongs to the application of a dielectric medium in the field of electrical equipment insulation, and particularly relates to a power electrical equipment with self-recovery insulation properties and a method for using the same.

Background technique

In the research and development of power electrical equipment, high-voltage electrical equipment, gas switches and other products, the insulation problem between electrical components and equipment is often involved, and the insulation characteristics directly determine the performance and reliability of the product. The widely used volume insulating solid dielectrics (such as epoxy resin, etc.) usually have high hardness and melting point, and have strong adhesion to the device. Once the breakdown occurs between internal components, the insulation cannot be restored. Replace the insulation. The difficulty of the medium is also very high, which usually leads to the scrapping of the entire equipment, which limits the repeated application and causes a lot of waste.

SUMMARY OF THE INVENTION

In order to solve the problem that the existing epoxy resin as the insulating medium of electric power equipment in the background cannot restore the insulation after breakdown, it must be replaced. Due to the difficulty of replacement, the entire equipment may be damaged or even scrapped. Power and electrical equipment with self-recovery performance and method of use thereof.

The technical scheme of the present invention is as follows:

The present invention provides a self-recovery electric power equipment with insulating properties, comprising a casing and a plurality of electrical components arranged in the casing; paraffin wax is arranged between the plurality of electrical components and between the electrical components and the casing , the breakdown strength of paraffin is greater than the field strength between electrical components.

Further, the above-mentioned electric power equipment further includes a heating unit disposed inside the casing.

Further, the above-mentioned electric power equipment further includes a state monitoring unit disposed inside the housing and located near each electrical component, and the state monitoring unit is connected with the heating unit.

Further, the above-mentioned paraffin is No. 80 microcrystalline paraffin, and its DC breakdown field strength is more than 200kV/mm.

Further, the above-mentioned state monitoring unit is a voltage sensor or a current sensor or a temperature sensor or an ultrasonic detection element for detecting partial discharge.

Based on the above description of the structure of the power and electrical equipment, the method for self-recovery of insulation performance when using the equipment is now introduced, which specifically includes the following steps:

Step 1: Judgment of breakdown phenomenon

The state monitoring unit detects and judges the electrical signals near the electrical components inside the housing in real time. When the electrical signals are abnormal, it is considered that the paraffin near the electrical components has a breakdown discharge phenomenon;

Step 2: Determine the heating and melting time of paraffin;

Calculate the heating and melting time of paraffin according to the volume, density, specific heat capacity and heating power of the paraffin insulating medium set in the shell;

Step 3: Restoration of the insulating properties of paraffin;

According to the electrical signal measured by the state monitoring unit, the heating unit is controlled to start heating, so that the paraffin begins to melt. When the heating and melting time of the paraffin is reached, the state monitoring unit controls the heating unit to disconnect the heating, and the paraffin begins to cool and solidify to the original state;

Repeat the heating-cooling process 2 times or more, and the paraffin insulation performance will recover.

Further, the above-mentioned electrical signal is a voltage signal or a current signal or a temperature signal or an ultrasonic signal of partial discharge.

The beneficial technical effects that the present invention has are as follows:

1. A state monitoring unit and a heating unit are added to the housing of the electric power equipment of the present invention, and the operating state of the electrical components (whether a breakdown occurs) is monitored by the state monitoring unit. When a breakdown occurs, the heating unit can be started in real time The heating-cooling process is repeated twice or more for the paraffin, so the equipment can automatically complete the insulation recovery without manual replacement and maintenance, avoiding equipment damage. In addition, the use of paraffin wax still has comparable breakdown voltage characteristics when it is melted into a liquid state, and it is even possible to achieve state recovery without shutdown.

2. The present invention adopts paraffin as the volume insulating material of electrical equipment or components, the cost of paraffin material is lower, and the preparation process is simpler; The insulation performance of the components is required, and the insulation volume can be reduced.

Description of drawings

Fig. 1 is a kind of structural representation of the present invention;

Figure 2 shows the breakdown voltage values of No. 80 microcrystalline paraffin under different field spacings;

Figure 3 is the breakdown voltage distribution value of liquid No. 80 microcrystalline paraffin and transformer oil;

Figure 4 is a photo of the residual carbonization channel after paraffin as an insulating medium breakdown;

Figure 5 is a photo after paraffin breakdown and re-preparation by heating and melting-cooling and solidification;

Figure 6 is a photo of paraffin breakdown and re-preparation after two heating and melting-cooling and solidification;

7 is a schematic structural diagram of the present invention applied to a dry-type transformer;

Detailed ways

In order to make the purpose, advantages and features of the present invention clearer, the following describes a power electrical device with self-recovery insulation performance and a method of using the same proposed by the present invention with reference to the accompanying drawings and specific embodiments. The advantages and features of the present invention will become apparent from the following description and claims. It should be noted that: the accompanying drawings are all in a very simplified form and use inaccurate scales, and are only used to facilitate and clearly assist in explaining the purpose of the embodiments of the present invention; secondly, the structures shown in the accompanying drawings are often actual structures. part.

Referring to FIG. 1 , a specific embodiment of a power electrical device with self-recovery insulation properties includes a housing 1, an electrical component 2, a heating unit 4 and a state monitoring unit 5 arranged in the housing 1; the electrical component 2 has at least one only (two electrical components in this embodiment); paraffin 3 is provided between each electrical component 2 and between the electrical component 2 and the housing 1, and the breakdown strength of the paraffin 3 is greater than the field strength between the electrical components 2 (In this embodiment, the paraffin is No. 80 microcrystalline paraffin, and its DC breakdown field strength is greater than 200kV/mm); the state monitoring unit 5 is installed inside the casing 1 and is located near the electrical component 2, and the state monitoring unit 5 and the heating unit 4 It is connected to control the opening or closing of the heating unit 4 .

Through the above brief description of the structure of power and electrical equipment, the method of how to perform self-recovery of insulation performance when using the equipment is described below:

Step 1: Judgment of breakdown phenomenon

The state monitoring unit (multiple) monitors the voltage, current, temperature inside and outside the machine, and ultrasonic signals generated by partial discharge near the electrical components inside the housing in real time. When the signal is abnormal, it is considered that the paraffin near the electrical components has a breakdown discharge. Phenomenon;

Step 2: Determine the heating and melting time of paraffin;

Calculate the heating and melting time of paraffin according to the volume, density, specific heat capacity and heating power of the paraffin insulating medium set in the shell;

Step 3: Restoration of the insulating properties of paraffin;

The state monitoring unit controls the heating unit to start heating, so that the paraffin begins to melt. When the heating and melting time of the paraffin is reached, the state monitoring unit controls the heating unit to turn off the heating, and the paraffin begins to cool and solidify to the original state. The preparation process is repeated twice or more to ensure the recovery of the insulating properties of the paraffin wax.

In order to better prove the authenticity, effectiveness and innovation of the present invention, the present invention also provides a test process to further illustrate the invention:

1. Test of breakdown characteristics of solid paraffin:

First, the breakdown characteristics of paraffin were tested, and the results are shown in Figure 2. Paraffin, which can be melted and solidified at a lower temperature, was selected as a substitute for the traditional solid insulating dielectric. Considering that the working temperature should not be too low, 80 microcrystals were selected. Paraffin as the test specific object.

Paraffin is a weakly polar (neutral) dielectric with more conductivity loss, and its insulating properties under a DC electric field are mainly used as a reference. In the test, a ball electrode with a diameter of 10mm, a plate electrode with a diameter of 10mm and a tip electrode with a diameter of 10mm at the bottom were used to form the ball-plate gap and the tip-plate gap. DC breakdown characteristics under uniform field and extremely non-uniform field, and the voltage polarity is reversed under the tip-plate gap to verify its polarity effect, considering the control of dissolved bubbles inside the paraffin, the vacuum sealing heating method is adopted, and the vacuum is used for heating Heating box, pump the air pressure in the box to below 90Pa, in order to avoid the chemical reaction of paraffin caused by high temperature, the preparation temperature is controlled at 100℃, and the sample is cooled in a vacuum environment (the pressure is less than 90Pa), so that the paraffin melts and immerses the electrode After cooling and solidification, a paraffin sample is made; the DC breakdown characteristics of the sample are tested; the results show that the breakdown field strength of No. 80 paraffin under a DC uniform field reaches 200kV/mm.

2. Characteristic test of liquid paraffin

As shown in Fig. 3, the breakdown voltage of paraffin in the liquid state was measured. Under the uniform field gap of 1.5mm, the average breakdown voltage of paraffin heated in vacuum at 100℃ in liquid state is 31.73kV, and the lowest value is 24.4kV; the average breakdown voltage of paraffin heated in air at 100℃ in liquid state It is 17.67kV, and the minimum value is 14.6kV; considering that the average breakdown voltage of transformer oil under the same gap at room temperature is 30.7kV, and the minimum value is 24.2kV, so even if the paraffin material melts in use, its breakdown voltage is still the same as that of transformer oil. Quite, it provides an idea for the non-stop recovery of insulation.

3. Characteristics recovery test after paraffin breakdown

Aiming at the characteristics that solid insulation is difficult to recover after breakdown, the influence of re-preparation on the insulation properties of paraffin was studied. The results show that the insulating properties can be restored after the paraffin breakdown and repeated preparation, and its breakdown voltage does not drop. In the test, a hemispherical electrode with a diameter of 5 mm and a plate electrode with a diameter of 10 mm are used to form a small ball-plate electrode, and a DC voltage is applied to both ends for a breakdown test under a fixed gap of 0.2 mm. After the breakdown of the sample, it is directly put into the vacuum heating box again for the preparation process of melting-cooling-solidification. After the breakdown, the breakdown samples were re-prepared 1 and 2 times respectively. It can be found that the breakdown residual carbonization channel could not be eliminated by one re-preparation, but could be eliminated by two re-preparations.

Figure 4 is a photo of the residual carbonization channel after the breakdown of paraffin as an insulating medium, and the carbonization channel affects the insulation of paraffin. Figure 5 is a photo of the presence of carbonized channels between electrodes when the paraffin is re-prepared after breakdown and taken out in a liquid state. It can be seen that there are still carbonized channels after the first heating and melting; Figure 6 is a liquid state when re-prepared twice A photo of the carbonized channel between the electrodes having been eliminated when taken out.

Table 1 presents the theoretical analysis results of the paraffin breakdown voltage probability. The fact that paraffin can melt at a lower temperature proves that it is easy to remove and replace the insulating material by heating after internal breakdown. Experiments have shown that the breakdown data of paraffin wax after breakdown and re-preparation are close to the breakdown data of new materials. Table 1 shows that the No. 80 microcrystalline paraffin obtained by normal distribution and Weibull distribution fitting is refueled after breakdown. and 50% and 5% breakdown voltage data for both cases where the carbonization channel is eliminated by heating. Referring to the third-order polynomial fitting results, the three-parameter Weibull distribution fitting value should be used to predict the breakdown voltage with lower probability. It can be seen that after the paraffin breakdown, melting the breakdown paraffin and eliminating the carbonization channel can achieve the same insulating effect as the non-breakdown. In practical applications, the process of repeated breakdown and repeated melting and cooling of the insulating material does not occur, so it can be considered that after the breakdown, the paraffin can be re-prepared to eliminate the carbonization channel to restore its insulating properties.

Table 1 The paraffin breakdown voltage probability calculated by fitting the three distributions

Fourth, the application of paraffin as an insulating medium in power and electrical equipment

Referring to Figure 7, taking a dry-type transformer as an example, the insulation is divided into inner insulation and outer insulation. The outer insulation is mainly completed by components such as bushings. . Internal insulation can be divided into main insulation and longitudinal insulation. The main insulation includes the insulation between the high and low voltage windings, the insulation between the phases and the ground, the insulation between the lead wire and the tap changer and the insulation between other windings. Longitudinal insulation is mainly the insulation between each turn of the winding and other components in the same winding. The online monitoring system of dry-type transformers has become mature, and the main physical quantities monitored include operating current, humidity, temperature, and partial discharge pulse signals. In paraffin-insulated dry-type transformers, since paraffin can be melted and poured repeatedly, current transformers, voltage sensors, temperature sensors, humidity sensors and ultrasonic sensors for measuring partial discharge signals can be installed inside the equipment. The electrical components, paraffin insulating medium, sensors, heating resistance wires, etc. can be sealed by the sealed shell, and the model calculation can be carried out through the real-time data of each sensor. If the situation is too large, the computer control system will order the equipment to stop, start heating in the area where the local insulation problem occurs, and control the heating by calculating the heat required for melting the paraffin wax under the conditions of the altitude and ambient temperature of the equipment installation area and the power of the heater. time and cooling time, restart the equipment test after ensuring that the paraffin insulation in the area has cooled and solidified.

The above description is only an embodiment of the present invention, and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the scope of the claims of the present invention.

Claims (7)

1. An electric power and electrical equipment with self-recovery of insulation performance comprises a shell (1) and a plurality of electric elements (2) arranged in the shell (1); the method is characterized in that: paraffin (3) is arranged among the plurality of electric elements (2) and between the electric elements (2) and the shell (1), and the breakdown strength of the paraffin (3) is greater than the field strength among the electric elements.

2. The electrical power apparatus with self-healing of insulating properties according to claim 1, characterized in that: the heating device also comprises a heating unit (4) arranged inside the shell (1).

3. The electrical power apparatus with self-healing of insulating properties according to claim 2, characterized in that: the electric heating device is characterized by further comprising a state monitoring unit (5) which is arranged inside the shell (1) and is positioned near each electric element (2), wherein the state monitoring unit (5) is communicated with the heating unit (4).

4. The electrical power apparatus with self-healing of insulating properties according to claim 2, characterized in that: the paraffin is No. 80 microcrystalline paraffin, and the direct current breakdown field strength of the paraffin is more than 200 kV/mm.

5. The power electrical apparatus with self-recovery of insulation performance of claim 3, characterized in that: the state monitoring unit is a voltage sensor, a current sensor, a temperature sensor or an ultrasonic detection element for detecting partial discharge.

6. A use method of electric power and electric equipment with self-recovery insulating property is characterized by comprising the following steps:

step 1: breakdown phenomenon determination

The state monitoring unit detects and judges the electric signals near the electric element in the shell in real time, and when the electric signals are abnormal, the paraffin near the electric element is considered to be subjected to breakdown discharge;

step 2: determining the heating and melting time of the paraffin;

calculating the heating and melting time of the paraffin according to the volume, density, specific heat capacity and heating power of a paraffin insulation medium arranged in the shell;

and step 3: recovering the insulating property of the paraffin;

controlling the heating unit to start heating according to the electric signal measured by the state monitoring unit so as to enable the paraffin to start melting, and controlling the heating unit to stop heating and the paraffin to start cooling and solidifying to an original state by the state monitoring unit after the heating and melting time of the paraffin is reached;

the heating-cooling process was repeated 2 times or more, and the paraffin insulation performance was recovered.

7. Use of the electrical power equipment with self-recovery of insulation properties according to claim 6, characterized in that: the electric signal is a voltage signal or a current signal or a temperature signal or an ultrasonic signal of partial discharge.

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