CN105203856B - A kind of Oil-Paper Insulation electric field strength calculates method and apparatus - Google Patents

Abstract

The present application discloses a calculation method and device for electric field strength of an oil-paper insulation system. When calculating the electric field strength of the oil-paper insulation system, the present invention first calculates the electric field strength of the space charge of the oil-paper insulation system according to the space charge density, and then calculates the electric field strength of the entire oil-paper insulation system. This method can characterize the electric field distortion of the oil-paper insulation system by considering the space charge effect in the process of calculating the electric field intensity of the entire oil-paper insulation system, thereby improving the calculation accuracy of the electric field intensity of the oil-paper insulation system.

Description

Method and device for calculating electric field strength of oil-paper insulation system

technical field

The present application relates to the field of direct current transmission, and more specifically, relates to a method and device for calculating electric field strength of an oil-paper insulation system.

Background technique

The converter transformer is an important device in the DC transmission system. Its valve side winding will bear the DC voltage component during normal operation, resulting in the accumulation of space charges at the interface between the insulating oil and the cardboard. In the analysis and test of the polarity reversal of the converter transformer, the influence of space charge on the electric field distribution and dielectric insulation has been the focus of attention.

The influence of space charge on the electric field distribution in an insulating system is mainly based on the Maxwell-Wagner equation (Maxwell-Wagner) theory. It relies on the conductivity and dielectric constant of two different materials. However, this principle is only applicable to linear materials, and does not take into account the electric field distortion of the oil-paper insulation system caused by the existence of space charges, which makes the calculation accuracy of the electric field strength obtained in the calculation of the oil-paper insulation system low. .

Contents of the invention

In view of this, this application provides a method and device for calculating the electric field strength of the oil-paper insulation system, which calculates the electric field strength of the space charge of the oil-paper insulation system through the space charge density, and then calculates the electric field strength of the entire oil-paper insulation system, taking into account the space charge effect The influence of the influence improves the calculation accuracy of the electric field strength of the oil-paper insulation system.

In order to achieve the above purpose, the proposed scheme is as follows:

A method for calculating the electric field strength of an oil-paper insulation system, comprising:

The oil-paper insulation system is divided into several equal parts, and the first space charge density curves of each equal part oil-paper insulation system at multiple preset moments are obtained, and the first space charge density curve is a curve of space charge density changing with position ;

According to the first space charge density curve, calculate the average space charge density of each equal portion of the oil-paper insulation system at the plurality of preset moments;

According to the average space charge density at the plurality of preset moments, construct the second space charge density curve of each equal portion of the oil-paper insulation system, and determine the relational expression corresponding to the second space charge density, the second space The charge density curve is the curve of space charge density changing with time;

Calculate the electric field strength of the space charge of each equal portion of the oil-paper insulation system according to the relational expression corresponding to the second space charge density curve of each equal portion of the oil-paper insulation system;

Use Maxwell's formula to calculate the electric field strength applied by the external power supply to each equal part of the oil-paper insulation system;

According to the electric field strength of the space charge and the electric field strength applied by the external power supply, the electric field strength of each equal part of the oil-paper insulation system is calculated.

Preferably, the acquiring the first space charge density curves of each aliquot at multiple preset moments includes:

Based on the electroacoustic pulse test system, the measured charge density curves of each equal portion of the oil-paper insulation system at the plurality of preset moments are obtained, and the measured charge density curves are curves of space charges changing with positions;

The first space charge density curve is constructed by subtracting the charge density at the electrode from the measured charge density.

Preferably, the calculation of the electric field strength of the space charge of each equal portion of the oil-paper insulation system according to the relational expression corresponding to the second space charge density curve of each equal portion of the oil-paper insulation system includes:

Use the calculation formula Calculate the electric field strength of the space charge for each equal portion of the oil-paper insulation system;

Wherein, E(x) is the electric field strength of space charge, ρ(x) is the relational expression corresponding to the second space charge density curve, ε _r is the relative permittivity of the oil-paper insulation system of this equal portion, ε ₀ is the vacuum dielectric Electrical constant, d is the thickness of the equal parts oil-paper insulation system.

A device for calculating the electric field strength of an oil-paper insulation system, comprising:

The first space charge density curve acquisition unit is used to divide the oil-paper insulation system into several equal parts, and obtain the first space charge density curve of each equal part of the oil-paper insulation system at multiple preset moments, the first space charge The density curve is the curve of the space charge density changing with the position;

A first calculation unit, configured to calculate the average space charge density of each equal portion of the oil-paper insulation system at the plurality of preset moments according to the first space charge density curve;

The second space charge curve construction unit is used to construct the second space charge density curve of each equal portion of the oil-paper insulation system according to the average space charge density at the plurality of preset moments, and determine the second space charge density According to the corresponding relational expression, the second space charge density curve is a curve of space charge density changing with time;

The second calculation unit is used to calculate the electric field strength of the space charge of each equal portion of the oil-paper insulation system according to the relational expression corresponding to the second space charge density curve of each equal portion of the oil-paper insulation system;

The third calculation unit is used to calculate the electric field strength applied by the external power supply to each equal portion of the oil-paper insulation system by using Maxwell's formula;

The fourth calculation unit is used to calculate the electric field strength of each equal part of the oil-paper insulation system according to the electric field strength of the space charge and the electric field strength applied by the external power supply.

Preferably, the first space charge density curve acquisition unit includes:

The oil-paper insulation system is divided into subunits, which are used to divide the oil-paper insulation system into several equal parts;

The measured charge density curve acquisition unit is used to obtain the measured charge density curves of each equal portion of the oil-paper insulation system at the plurality of preset moments based on the electroacoustic pulse test system, and the measured charge density curve is the space charge The curve of position change;

The first space charge density curve construction subunit is configured to subtract the charge density at the electrode from the measured charge density to construct the first space charge density curve.

It can be known from the above technical solution that the present application discloses a method and device for calculating electric field strength of an oil-paper insulation system. In this method, the oil-paper insulation system is divided into several equal parts, and the distribution curve of the charge density changing with the position of each equal part at multiple preset moments is obtained, so as to determine the distribution curve of each equal part of the oil-paper insulation system at multiple preset moments. The average charge density, in turn, determines the profile of the charge density versus time for each aliquot of the oil-paper insulation system. Since the thickness of each equal portion of the oil-paper insulation system is extremely small, it can be considered that the charge density of the equal portion of the oil-paper insulation system is equal at the same time. Therefore, the electric field strength of each equal part of the oil-paper insulation system at any time can be calculated according to the change curve of the charge density with time, and then the electric field strength of the equal part of the oil-paper insulation system can be calculated according to the electric field strength applied by the external power supply to the equal part. Electric field strength. Compared with the prior art, when calculating the electric field strength of the oil-paper insulation system, the present invention first calculates the electric field strength of the space charge of the oil-paper insulation system according to the space charge density, and then calculates the electric field strength of the entire oil-paper insulation system, taking into account the space charge effect The influence of the influence improves the calculation accuracy of the electric field strength of the oil-paper insulation system.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only It is an embodiment of the present invention, and those skilled in the art can also obtain other drawings according to the provided drawings without creative work.

Fig. 1 shows a schematic flow chart of an electric field intensity calculation method of an oil-paper insulation system disclosed in an embodiment of the present invention;

Fig. 2 shows a schematic structural diagram of an electric field strength calculation device for an oil-paper insulation system disclosed in another embodiment of the present invention.

Detailed ways

The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some, not all, embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

Referring to FIG. 1 , it shows a schematic flowchart of a method for calculating electric field strength of an oil-paper insulation system disclosed by an embodiment of the present invention.

As can be seen from Figure 1, the method includes:

S101: Divide the oil-paper insulation system into several equal parts, and obtain the first space charge density curves of each equal part of the oil-paper insulation system at multiple preset moments.

It should be noted that the first space charge density curve is a curve of space charge density changing with position, which can be obtained by an electroacoustic pulse-based testing system.

The specific method is as follows:

The measured charge density curves of the oil-paper insulation system at multiple preset moments are obtained by using the electro-acoustic pulse test system. The charge density at the electrode is subtracted from the measured charge density to eliminate the influence of the charge on the plate, and then the first space charge density curve is constructed.

S102: According to the first space charge density curve, calculate the average space charge density of each equal portion of the oil-paper insulation system at the plurality of preset moments.

Due to the small thickness of the oil-paper insulation system itself, for the oil-paper insulation system in the same equal portion, the space charge density of the oil-paper insulation system in the equal portion is equal everywhere. In the present invention, the average space charge density of the equal portion of the oil-paper insulation system can be used as the space charge density of the equal portion of the oil-paper insulation system at a preset time.

S103: Construct a second space charge density curve of each equal portion of the oil-paper insulation system according to the average space charge density at the plurality of preset moments, and determine a relational expression corresponding to the second space charge density.

For each equal part of the oil-paper insulation system, a coordinate system is established, with time as the abscissa and space charge density as the ordinate, and multiple coordinate points are determined according to the average space charge density at multiple preset times, and multiple coordinates Points are fitted to obtain the space charge density curve of each equal part of the oil-paper insulation system with time, that is, the second space charge density curve, and the corresponding relational formula is determined.

S104: According to the relational expression corresponding to the second space charge density curve of each equal portion of the oil-paper insulation system, calculate the electric field strength of the space charge of each equal portion of the oil-paper insulation system.

The specific implementation is as follows:

Use the calculation formula Calculate the electric field strength of the space charge for each aliquot of the oil-paper insulation system.

Wherein, E (x) is the electric field strength of the space charge of the oil-paper insulation system of this equal portion, ρ (x) is the relational expression corresponding to the second space charge density curve, ε _r is the relative medium of the oil-paper insulation system of this equal portion Electrical constant, ε ₀ is the vacuum dielectric constant, d is the thickness of the equal parts oil-paper insulation system.

S105: Using Maxwell's formula to calculate the electric field strength applied by the external power supply to each equal portion of the oil-paper insulation system.

S106: Calculate the electric field strength of each equal part of the oil-paper insulation system according to the electric field strength of the space charge and the electric field strength applied by the external power supply.

Among them, the electric field strength of each equal portion of the oil-paper insulation system is the superposition of the electric field strength of the space charge and the electric field strength of the external power supply time.

It can be known from the above embodiments that the present application discloses a method for calculating the electric field intensity of an oil-paper insulation system. In this method, the oil-paper insulation system is divided into several equal parts, and the distribution curve of the charge density changing with the position of each equal part at multiple preset moments is obtained, so as to determine the distribution curve of each equal part of the oil-paper insulation system at multiple preset moments. The average charge density, in turn, determines the profile of the charge density versus time for each aliquot of the oil-paper insulation system. Since the thickness of each equal portion of the oil-paper insulation system is extremely small, it can be considered that the charge density of the equal portion of the oil-paper insulation system is equal at the same time. Therefore, the electric field strength of each equal part of the oil-paper insulation system at any time can be calculated according to the change curve of the charge density with time, and then the electric field strength of the equal part of the oil-paper insulation system can be calculated according to the electric field strength applied by the external power supply to the equal part. Electric field strength. Compared with the prior art, when calculating the electric field strength of the oil-paper insulation system, the present invention first calculates the electric field strength of the space charge of the oil-paper insulation system according to the space charge density, and then calculates the electric field strength of the entire oil-paper insulation system, taking into account the space charge effect The influence of the influence improves the calculation accuracy of the electric field strength of the oil-paper insulation system.

Referring to FIG. 2 , it shows a schematic structural diagram of an electric field intensity calculation device for an oil-paper insulation system disclosed in another embodiment of the present invention.

As can be seen from Figure 2, the device includes: a first space charge density curve acquisition unit 1, a first calculation unit 2, a second space charge curve construction unit 3, a second calculation unit 4, a third calculation unit 5 and a fourth calculation unit 6.

Wherein, the first space charge density curve acquisition unit is used to divide the oil-paper insulation system into several equal parts, and acquire the first space charge density curves of each equal part of the oil-paper insulation system at multiple preset moments. Wherein, the first space charge density curve is a curve of space charge density changing with position.

Furthermore, the first calculation unit calculates the average space charge density of each equal portion of the oil-paper insulation system at the plurality of preset moments according to the first space charge density curve.

The second space charge curve construction unit then constructs the second space charge density curve of each equal portion of the oil-paper insulation system according to the average space charge density at the plurality of preset moments, and determines the corresponding Relational. Wherein, the second space charge density curve is a curve of space charge density changing with time.

The second calculation unit calculates the electric field strength of the space charge of each equal portion of the oil-paper insulation system according to the relational expression corresponding to the second space charge density curve of each equal portion of the oil-paper insulation system.

The third calculation unit is used to calculate the electric field strength applied by the external power supply to each equal portion of the oil-paper insulation system by using Maxwell's formula.

Further, the fourth computing unit calculates the electric field strength of each equal portion of the oil-paper insulation system according to the electric field strength of the space charges and the electric field strength applied by the external power supply.

It should be noted that the apparatus embodiment is compatible with the method embodiment, and the execution mode and working principle of each unit thereof are consistent with the description in the method embodiment, so details are not repeated here.

Optionally, in other device embodiments disclosed in the present invention, the first space charge density curve acquisition unit of the device specifically includes: an oil-paper insulation system division subunit, a measured charge density curve acquisition unit, and a first space charge density curve construction subunit.

Wherein, the oil-paper insulation system is divided into subunits, which are used to divide the oil-paper insulation system into several equal parts.

The measured charge density curve acquisition unit is used to obtain the measured charge density curves of each equal portion of the oil-paper insulation system at the plurality of preset moments based on the electroacoustic pulse test system, and the measured charge density curve is the space charge The curve of position change.

The first space charge density curve construction subunit is configured to subtract the charge density at the electrode from the measured charge density to construct the first space charge density curve.

The difference from the previous embodiment is that the space charge density used to calculate the space charge electric field strength in this embodiment is the measured space charge density minus the charge density at the electrode, so as to eliminate the influence of the charge on the plate and improve the calculation accuracy.

Finally, it should also be noted that in this text, relational terms such as first and second etc. are only used to distinguish one entity or operation from another, and do not necessarily require or imply that these entities or operations, any such actual relationship or order exists. Furthermore, the term "comprises", "comprises" or any other variation thereof is intended to cover a non-exclusive inclusion such that a process, method, article, or apparatus comprising a set of elements includes not only those elements, but also includes elements not expressly listed. other elements of or also include elements inherent in such a process, method, article, or device. Without further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of additional identical elements in the process, method, article or apparatus comprising said element.

Each embodiment in this specification is described in a progressive manner, each embodiment focuses on the difference from other embodiments, and the same and similar parts of each embodiment can be referred to each other.

The above description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the present invention will not be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims (5)

1. a kind of Oil-Paper Insulation electric field strength calculates method, which is characterized in that including：

Oil-Paper Insulation is divided into several equal portions, obtains the Oil-Paper Insulation of each equal portions the of multiple predetermined times One space charge density curve, the first space charge density curve are space charge density with the curve of change in location；

According to the first space charge density curve, the Oil-Paper Insulation of each equal portions is calculated in the multiple predetermined time Mean space charge density；

According to the mean space charge density of the multiple predetermined time, construct the Oil-Paper Insulation of each equal portions second is empty Between charge density curve, and determine the corresponding relational expression of the second space charge density, the second space charge density is bent Line is the curve that space charge density changes over time；

According to the corresponding relational expression of second space charge density curve of the Oil-Paper Insulation of each equal portions, each equal portions are calculated Oil-Paper Insulation space charge electric field strength；

The electric field strength of Oil-Paper Insulation application of the additional power source to each equal portions is calculated using Maxwell's formula；

According to the electric field strength that the electric field strength of the space charge and additional power source apply, each equal portions paper oil insulation system is calculated The electric field strength of system.

2. according to the method described in claim 1, it is characterized in that, described obtain each equal portions the first of multiple predetermined times Space charge density curve, including：

Based on electroacoustic pulse test system, the actual measurement in the multiple predetermined time of the Oil-Paper Insulation of each equal portions is obtained Charge density curve, the actual measurement charge density curve are space charge with the curve of change in location；

Charge density at electrode is subtracted using charge density is surveyed, builds the first space charge density curve.

3. according to the method described in claim 1, it is characterized in that, the second of the Oil-Paper Insulation according to each equal portions The corresponding relational expression of space charge density curve calculates the electric field strength of the space charge of the Oil-Paper Insulation of each equal portions, Including：

Utilize calculation formulaCalculate the space charge of the Oil-Paper Insulation of each equal portions Electric field strength；

Wherein, E (x) be space charge electric field strength, ρ (x) be the corresponding relational expression of second space charge density curve, ε_rIt is The relative dielectric constant of the Oil-Paper Insulation of the equal portions, ε₀It is permittivity of vacuum, d is the thickness of the equal portions Oil-Paper Insulation Degree.

4. a kind of Oil-Paper Insulation electric field strength calculates device, which is characterized in that including：

First space charge density curve collecting unit for Oil-Paper Insulation to be divided into several equal portions, is obtained per first-class The Oil-Paper Insulation of part is in the first space charge density curve of multiple predetermined times, the first space charge density curve It is space charge density with the curve of change in location；

First computing unit, for according to the first space charge density curve, calculating the Oil-Paper Insulation of each equal portions In the mean space charge density of the multiple predetermined time；

Second space charge curve construction unit, for the mean space charge density according to the multiple predetermined time, construction The second space charge density curve of the Oil-Paper Insulation of each equal portions, and determine that the second space charge density is corresponding Relational expression, the second space charge density curve are the curve that space charge density changes over time；

Second computing unit, for the corresponding pass of second space charge density curve of the Oil-Paper Insulation according to each equal portions It is formula, calculates the electric field strength of the space charge of the Oil-Paper Insulation of each equal portions；

Third computing unit applies the Oil-Paper Insulation of each equal portions for calculating additional power source using Maxwell's formula Electric field strength；

4th computing unit for the electric field strength that the electric field strength according to the space charge and additional power source apply, calculates The electric field strength of each equal portions Oil-Paper Insulation.

5. device according to claim 4, which is characterized in that the first space charge density curve collecting unit, packet It includes：

Oil-Paper Insulation divides subelement, for Oil-Paper Insulation to be divided into several equal portions；

Charge density curve collecting unit is surveyed, for being based on electroacoustic pulse test system, obtains the paper oil insulation of each equal portions The actual measurement charge density curve in the multiple predetermined time of system, the actual measurement charge density curve are space charge with position Put the curve of variation；

First space charge density curve builds subelement, for subtracting charge density at electrode using surveying charge density, Build the first space charge density curve.