阅读说明：本技术 一种典型对称电极间隙结构的有效场域特征集的表征方法 (Characterization method of effective field characteristic set of typical symmetric electrode gap structure ) 是由 邱志斌 吴子建 廖才波 朱雄剑 侯华胜 张楼行 于 2021-06-18 设计创作，主要内容包括：本发明公开了一种典型对称电极间隙结构的有效场域特征集的表征方法,该方法包括：构建对称电极间隙的仿真模型、划分有限元网格并计算静电场分布,提取两电极端部连线路径上的电场强度值,以该路径上的电场强度最小值作为边界值E-(cr),将两电极之间电场强度大于边界值的网格单元构成的区域定义为与间隙击穿具有强关联性的有效场域,并将其划分为高压电极子场域和接地电极子场域,在两个子场域内分别提取所有网格单元的电场强度和单元体积,并据此计算得出45个与电场分布有关的特征量,构成有效场域特征集,用以表征间隙结构。本发明提供的有效场域特征集可为研究触发间隙击穿的特征区域提供参考,适用于作为间隙击穿电压预测模型的输入参数。(The invention discloses a method for representing an effective field characteristic set of a typical symmetrical electrode gap structure, which comprises the following steps: constructing a simulation model of the symmetrical electrode gap, dividing a finite element grid, calculating electrostatic field distribution, extracting the electric field strength value on a connecting line path of the end parts of the two electrodes, and taking the minimum value of the electric field strength value on the connecting line path as a boundary value E cr Defining the area formed by grid cells with electric field intensity between two electrodes greater than boundary value as effective field area with strong correlation with gap breakdown, dividing it into high-voltage electrode sub-field area and grounding electrode sub-field area, respectively extracting electric field intensity and cell volume of all grid cells in two sub-fields, and calculating 45 characteristic quantities related to electric field distribution to form effective field area characteristic set for representing gap structure. The effective field characteristic set provided by the invention can provide reference for researching the characteristic region triggering the gap breakdown, and is suitable for being used as an input parameter of a gap breakdown voltage prediction model.)

1. A method for characterizing the effective field feature set of a typical symmetric electrode gap structure, said method comprising the steps of:

s1, constructing a simulation model of a symmetrical electrode gap, dividing a finite element grid, respectively applying a high potential U and a zero potential to the two electrodes, and calculating electrostatic field distribution;

s2, extracting the electric field intensity value on the path connecting the two electrode ends, and taking the minimum value of the electric field intensity on the path as a boundary value E_cr；

S3, defining an area formed by grid units with the electric field intensity between the two electrodes larger than a boundary value as an effective field area with strong relevance to gap breakdown, and dividing the effective field area into a high-voltage electrode sub-field area and a ground electrode sub-field area;

s4, respectively extracting the electric field intensity and the unit volume of all grid units in the two sub-fields, and calculating 45 characteristic quantities related to electric field distribution according to the electric field intensity and the unit volume to form an effective field characteristic set;

the effective field area feature set specifically includes:

volume V of high voltage electrode sub-field_hVolume V of the grounded electrode sub-field_lMinimum value E of electric field intensity on the path connecting the ends of the two electrodes_n；

Maximum value E of electric field intensity of high-voltage electrode sub-field_mhAverage value E_ahLarge value average value E_aehExtremely poor of_rhVariance E_varhStandard deviation E_stdhDistortion rate f_hTotal energy W of electric field_hEnergy density W_dhThe electric field intensity is greater than E_n+x·(E_mh-E_n) Unit volume V of_hxAnd electric field energy W_hxAnd the occupied V thereof_hVolume ratio of (V)_rhxAnd occupied W_hEnergy ratio W of_rhx；

Maximum value E of electric field intensity of grounded electrode sub-field_mlAverage value E_alLarge value average value E_aelExtremely poor of_rlVariance E_varlStandard deviation E_stdlDistortion rate f_lTotal energy W of electric field_lEnergy density W_dlThe electric field intensity is greater than E_n+x·(E_ml-E_n) Unit volume V of_lxAnd electric field energy W_lxAnd the occupied V thereof_lVolume ratio of (V)_rlxAnd occupied W_lEnergy ratio W of_rlx。

2. The method for characterizing the set of effective field characteristics of a typical symmetric electrode gap structure according to claim 1, wherein: x is 0.7, 0.8 and 0.9.

Technical Field

The invention belongs to the technical field of high voltage and insulation, and particularly relates to a method for representing an effective field characteristic set of a typical symmetric electrode gap structure.

Background

The discharge characteristic of the air gap is one of the fundamental problems of long-term concern in the field of high-voltage power transmission and transformation. Due to the lack of perfect discharge theory, insulation design only depends on discharge characteristic tests, and the relation of simple geometric parameters such as discharge voltage and gap distance is obtained through tests, however, the test research cost is high, the period is long, and air gap discharge voltage prediction research needs to be carried out. Typical symmetric electrode gaps such as spherical gaps, rod-rod gaps and the like have simple geometric structures and can be used as entry points for researching complex gap models. Simple geometric parameters such as electrode size, gap distance and the like reflect the structural characteristics of the gap and are important factors influencing gap discharge. However, the effect of representing the gap structure by simple geometric parameters is limited, i.e. the structural factors influencing the gap insulation characteristics cannot be accurately reflected. The gap structure is a macroscopic parameter for determining the spatial distribution of the electric field, and effective representation of the gap structure can be realized through a three-dimensional electric field with richer information.

In the field of air gap discharge research, the characteristic set of an electric field is adopted to characterize the gap structure, and relevant research is available. For example, in the disclosed technologies such as "new method for calculating breakdown voltage of slightly non-uniform electric field air gap" (high voltage technology, in 2015, 2 nd), and "prediction of electric field characteristic quantity of shortest path of spherical gap and power frequency breakdown voltage" (university of wuhan (engineering edition), in 2019, 11 th), it is proposed to use the characteristic quantities defined on "entire region, discharge channel, electrode surface, discharge path" or "shortest path" to characterize electric field distribution of entire gap. However, for typical symmetric electrode gaps such as the spherical gap and the rod-rod gap, characterization using the feature quantities of the regions such as "entire region, discharge channel, electrode surface, discharge path" and the like may cause feature redundancy, and the related feature quantities defined by the "shortest path" alone often have difficulty in comprehensively reflecting the spatial structure of the air gap. The spherical gap and the rod-rod gap are used as symmetrical gap structures, the distribution of the space electric fields of the spherical gap and the rod-rod gap has certain similarity, and in order to realize the uniform representation of the space electric fields of the spherical gap and the rod-rod gap, a characteristic extraction field area with a smaller range is required to be defined between the high-voltage electrode and the low-voltage electrode of the gap, so that a more concise and reasonable electric field distribution characteristic set is constructed.

Disclosure of Invention

Aiming at the defects and problems in the prior art, the invention aims to provide a method for representing an effective field characteristic set of a typical symmetric electrode gap structure, and provide basic characteristic parameters for reasonably representing three-dimensional space structures of a spherical gap and a rod-rod gap and further realizing breakdown voltage prediction.

The invention is realized by the following technical scheme:

a method of characterizing an effective field feature set of a typical symmetric electrode gap structure, the method comprising the steps of:

s1, constructing a simulation model of a symmetrical electrode gap, dividing a finite element grid, respectively applying a high potential U and a zero potential to the two electrodes, and calculating electrostatic field distribution;

s2, extracting the electric field intensity value on the path connecting the two electrode ends, and taking the minimum value of the electric field intensity on the path as a boundary value E_cr；

S3, defining an area formed by grid units with the electric field intensity between the two electrodes larger than a boundary value as an effective field area with strong relevance to gap breakdown, and dividing the effective field area into a high-voltage electrode sub-field area and a ground electrode sub-field area;

s4, respectively extracting the electric field intensity and the unit volume of all grid units in the two sub-fields, and calculating 45 characteristic quantities related to electric field distribution according to the electric field intensity and the unit volume to form an effective field characteristic set;

the effective field area feature set specifically includes:

volume V of high voltage electrode sub-field_hVolume V of the grounded electrode sub-field_lMinimum value E of electric field intensity on the path connecting the ends of the two electrodes_n；

Maximum value E of electric field intensity of high-voltage electrode sub-field_mhAverage value E_ahLarge value average value E_aehExtremely poor of_rhVariance E_varhStandard deviation E_stdhDistortion rate f_hTotal energy W of electric field_hEnergy density W_dhThe electric field intensity is greater than E_n+x·(E_mh-E_n) Unit volume V of_hxAnd electric field energy W_hxAnd the occupied V thereof_hVolume ratio of (V)_rhxAnd occupied W_hEnergy ratio W of_rhx；

Maximum value E of electric field intensity of grounded electrode sub-field_mlAverage value E_alLarge value average value E_aelExtremely poor of_rlVariance E_varlStandard deviation E_stdlDistortion rate f_lTotal energy W of electric field_lEnergy density W_dlThe electric field intensity is greater than E_n+x·(E_ml-E_n) Unit volume V of_lxAnd electric field energy W_lxAnd the occupied V thereof_lVolume ratio of (V)_rlxAnd occupied W_lEnergy ratio W of_rlx。

Further, x is 0.7, 0.8 and 0.9.

Compared with the prior art, the invention has the beneficial effects that:

(1) the invention adopts the electric field distribution characteristic set to describe the space structure of the symmetrical electrode gap structure such as the spherical gap and the rod-rod gap, can replace simple geometric parameters such as the gap distance, the spherical diameter, the rod electrode size and the like, and realizes more reasonable representation of the gap structure.

(2) Compared with the prior art that the space areas such as the whole area, the discharge channel, the electrode surface, the discharge path, the shortest path and the like are adopted for the characteristic definition of the electric field distribution, the effective field electric field distribution characteristic set provided by the invention has the advantages that the efficiency of characteristic extraction and the perfection of characteristic expression are both considered, the popularization performance is better, and the method is more suitable for being used as the input parameter of a gap breakdown voltage prediction model.

Drawings

FIG. 1 is a schematic diagram of an effective field characterizing a spherical gap structure in an embodiment;

FIG. 2 is a cloud diagram of the electrostatic field distribution of the spherical gap effective field in the example.

Detailed Description

The invention will be further described with reference to the accompanying drawings.

The present invention is further described in the following examples, which should not be construed as limiting the scope of the invention, but rather as providing the following examples which are set forth to illustrate and not limit the scope of the invention.

First, the concrete method principle of the invention

The invention provides an effective field characteristic set for representing a typical symmetric electrode gap structure, which is used for quantitatively describing the space structure and the electric field distribution of a spherical gap and a rod-rod gap and can provide basic characteristic parameters for further realizing breakdown voltage prediction.

The invention adopts the following technical scheme:

for the ball gap and the rod-rod air gap which are researched by high-voltage discharge, high voltage is usually applied to one end, the other end is grounded, a corresponding simulation model can be established according to the structure size, a finite element grid is divided, high potential U (namely, a high-voltage ball electrode 1) is applied to one electrode, zero potential (namely, a grounded ball electrode 2) is applied to the other electrode, and the electrostatic field distribution of the gap is calculated by utilizing a finite element method.

Firstly, an effective field extracted from the electric field distribution characteristics is defined between the two electrodes, in this embodiment, taking the spherical gap as an example, as shown in fig. 1, the electric field intensity value on the path connecting the end portions of the two electrodes is extracted, and the minimum value of the electric field intensity on the path is taken as a boundary value E_crThe region formed by grid cells with electric field intensity between two electrodes greater than the boundary value is defined as effective field region having strong correlation with gap breakdown, and is divided into high-voltage electrode sub-field 3 and grounding electrode sub-field 4The boundary value is the joint of the high-voltage electrode sub-field 3 and the grounding electrode sub-field 4, the electric field intensity and the unit volume of all grid units are respectively extracted from the two sub-fields, and 45 characteristic quantities related to electric field distribution are calculated according to the electric field intensity and the unit volume to form an effective field characteristic set, which is as follows:

volume V of the high-voltage electrode sub-field 3_hVolume V of the grounded electrode sub-field 4_lMinimum value E of electric field intensity on the path connecting the ends of the two electrodes_n：

Wherein n and m are the total number of cells in the high voltage electrode subfield 3 and the ground electrode subfield 4, respectively, E_kThe electric field intensity value of the kth sampling point on the connecting line of the end parts of the two electrodes is P, and P is the total number of the sampling points on the connecting line.

Maximum value E of the electric field strength of the high-voltage electrode sub-field 3_mhAverage value E_ahLarge value average value E_aehExtremely poor of_rhVariance E_varhStandard deviation E_stdhDistortion rate f_hThe calculation formula is as follows:

in the formula, E_iRepresents the average value of the field intensity of the ith unit of the high-voltage electrode sub-field 3, i is 1,2, …, n; e_sThe s-th field intensity in the field is larger than E_ahS is the corresponding total number of cells.

Total electric field energy W of high voltage electrode sub-field 3_hEnergy density W_dhThe electric field intensity is greater than E_n+x·(E_mh-E_n) Unit volume V of_hxAnd electric field energy W_hxAnd the occupied V thereof_hVolume ratio of (V)_rhxAnd occupied W_hEnergy ratio W of_rhxThe calculation formula is as follows:

in the formula, epsilon₀Is a vacuum dielectric constant, V_hxiAnd W_hxiThe electric field intensity of the ith electrode in the high-voltage electrode sub-field 3 is larger than E_n+x·(E_mh-E_n) X is the corresponding total number of cells, V_iAnd W_iThe volume and the energy of the ith unit are respectively, wherein the value of x is 0.7, 0.8 and 0.9.

Maximum value E of electric field strength of the ground electrode sub-field 4_mlAverage value E_alLarge value average value E_aelExtremely poor of_rlVariance E_varlStandard deviation E_stdlDistortion rate f_lThe calculation formula is as follows:

in the formula, E_jRepresents the average value of the j unit field intensity of the grounded electrode sub-field 4, j is 1,2, …, m; e_tThe t field intensity in the field is larger than E_alT is the corresponding total number of cells.

Total electric field energy W of the grounded electrode electron field 4_lEnergy density W_dlThe electric field intensity is greater than E_n+x·(E_ml-E_n) Unit volume V of_lxAnd electric field energy W_lxAnd the occupied V thereof_lVolume ratio of (V)_rlxAnd occupied W_lEnergy ratio W of_rlxThe calculation formula is as follows:

in the formula, V_hxjAnd W_hxjThe electric field intensity of the jth sub-field 3 of the high-voltage electrode is larger than E_n+x·(E_ml-E_n) Xm is the corresponding total number of cells, V_jAnd W_jThe volume and the energy of the jth unit are respectively, wherein the value of x is 0.7, 0.8 and 0.9.

Second, ball gap embodiment

This example illustrates a spherical gap as an example of an effective field characteristic set for characterizing a typical symmetric electrode gap structure according to the present invention. The sphere diameter D is 50cm, and the gap distance D is 10 cm. A two-dimensional axisymmetric simulation model is established according to the size, a potential of 1V is loaded on one end electrode, a zero potential is applied on the other electrode and the cut air boundary, the electrostatic field distribution can be calculated by adopting a finite element method, and the electric field simulation result is shown in figure 2.

Selecting 2001 sampling points on the connecting path of the two electrode ends at equal intervals, extracting the electric field intensity value of each sampling point, and taking the minimum value of the electric field intensity on the connecting path as a boundary value E_crAccording to the definition of the effective field, the electric field intensity and unit volume of all grid units in the high-voltage electrode sub-field 3 and the grounding electrode sub-field 4 are respectively extracted, and the effective field characteristic set is respectively calculated according to the characteristic calculation formula and is shown in table 1.

TABLE 1

From this, the effective field characteristic set of the spherical gap in this embodiment can be obtained, and the elements in the set are the above-mentioned 45 electric field distribution characteristic quantities.

The foregoing merely represents preferred embodiments of the invention, which are described in some detail and detail, and therefore should not be construed as limiting the scope of the invention. It should be noted that, for those skilled in the art, various changes, modifications and substitutions can be made without departing from the spirit of the present invention, and these are all within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.