CN114152727B - A soil risk assessment method for grounding grid considering moisture content - Google Patents

Abstract

The invention discloses a grounding grid soil risk assessment method considering moisture content, wherein a test platform in the grounding grid soil risk assessment method considering moisture content mainly comprises a direct current generating device, a direct current generating device controller, a direct current generating device grounding module, a current sensing device, a grounding grid external leading-out port, a numerical value acquisition module, a moisture sensor, a soil test box, a core control device and the like, and a grounding grid soil risk comprehensive assessment factor is obtained by measuring the moisture content of soil and direct current response of each section of the grounding grid.

Description

A soil risk assessment method for grounding grid considering moisture content

technical field

The invention belongs to the technical field of power system grounding, and particularly relates to a soil risk assessment method for a grounding grid considering moisture content.

Background technique

Power system grounding technology is an important and effective measure to ensure the safety of electrical equipment and personal safety in large power grids. It provides a channel for the dissipation of fault current or lightning, mainly through grounding devices or grounding systems. The construction and operation of the system play an irreplaceable role. Grounding is inseparable from the soil. At present, the research on the performance of the grounding grid body is the focus of domestic and foreign scholars. There is a lack of research on the risk of grounding grid soil considering different moisture contents, and there is also a lack of relevant risk assessment techniques. In nature, there are various geological environments, and the soil moisture content has an impact on the normal leakage of the grounding grid, which may lead to an abnormal increase in the potential of the grounding grid, causing serious damage to the insulation of the secondary equipment. In order to better improve the grounding stability and ensure the good insulation of the secondary equipment, it is urgent to study the soil risk assessment method for the grounding grid considering the moisture content. 's reference.

SUMMARY OF THE INVENTION

The purpose of the present invention is to solve the deficiencies of the prior art and provide a soil risk assessment method for the grounding grid considering the moisture content.

For achieving the above object, the technical scheme adopted in the present invention is as follows:

First, build a grounding grid soil risk test platform, which includes a DC generator, a DC generator controller, a DC generator grounding module, a first high-voltage cable, a current sensing device, an external outlet for the grounding grid, a value acquisition module, The first moisture sensor, the second moisture sensor, the soil test box, the grounding grid, the core control device, the grounding module of the test box;

Both the grounding module of the digital DC generator and the grounding module of the test box are reliably grounded;

The upper end of the DC generating device is electrically connected to the left end of the first high-voltage cable, the right end of the first high-voltage cable is electrically connected to the left end of the current sensing device, the right end of the current sensing device is electrically connected to the external lead-out port of the grounding grid, and the external lead-out port of the grounding grid is electrically connected It is electrically connected to the grounding grid, the lower end of the DC generating device is electrically connected to the upper end of the DC generating device controller, and the lower end of the DC generating device controller is electrically connected to the core control device;

The soil test box includes a first moisture sensor, a second moisture sensor, and a grounding grid. The first moisture sensor and the second moisture sensor are respectively electrically connected to the numerical value acquisition module, and the numerical value acquisition module is electrically connected to the core control device;

The second step is to measure the soil moisture content and the DC response of the grounding grid of each section:

The specific moisture content in the soil is measured by the first moisture sensor and the second moisture sensor to obtain the comprehensive soil moisture content W _p ; then the grounding grid is segmented according to the external lead-out port of the grounding grid, and direct current is performed for each section of the grounding grid. Working current test, the specific steps include: controlling the DC generator controller through the core control device, and setting the DC generator to output a DC working voltage with an amplitude of _UD , and measuring the DC working voltage of a certain section of the grounding grid through the current sensing device The DC working current I _sQ generated under the voltage is transmitted to the core control device through the value acquisition module, and the current output port and return port of the DC generating device are connected to the external lead-out port of the other segment of the grounding grid, and the above test steps are repeated. A total of q groups of DC working current sampling data are obtained;

The third step is to obtain the soil risk assessment factor E _1Q of the grounding grid:

In the above formula, E _1Q is the first assessment factor for the soil risk of the Q group grounding grid, _{IsQ is the DC working current of the Q group ground grid, I zQ is} the standard value of the DC working current of the Q group ground grid, and T is Grounding grid running time, q is the total number of test groups;

Substitute the measured comprehensive soil moisture content W _p into the above formula to obtain the second evaluation factor E ₂ of the soil hazard characteristics of the grounding grid:

In the fourth step, based on the above steps, the comprehensive evaluation factor E of the soil risk of the grounding grid based on the moisture content is obtained:

Wherein S ₁ is the first benchmark weight factor, and S ₂ is the second benchmark weight factor;

When E ∈ (0, 0.14], it indicates that the soil risk of the grounding grid is outstanding, and the grounding system needs to be replaced or repaired immediately; when E ∈ (0.14, +∞), it indicates that the soil risk of the grounding grid is general and can be properly maintained on a regular basis.

Compared with the prior art, the present invention has the following beneficial effects:

1) The present invention proposes an evaluation method that can consider segmentation sampling and weighting factors;

2) The evaluation method in the present invention can obtain the comprehensive evaluation factor of the soil risk of the grounding grid based on the moisture content, and carry out the risk evaluation of the grounding soil.

Description of drawings

1 is a schematic diagram of the overall structure of the grounding grid soil risk testing platform when the present invention is used;

Detailed ways

The present invention will be further described in detail below in conjunction with the accompanying drawings.

It can be seen from Fig. 1 that the experimental platform and method provided by the present invention comprise the following steps:

The first step is to build a grounding grid soil risk testing platform, which includes a DC generating device (1), a DC generating device controller (2), a DC generating device grounding module (3), a first high-voltage cable (4), A current sensing device (5), a grounding grid external lead-out port (7), a numerical value acquisition module (8), a first moisture sensor (9), a second moisture sensor (10), a soil test box (11), a grounding grid ( 12), core control device (13), test box grounding module (33);

The grounding module (3) of the digital DC generating device and the grounding module (33) of the test box are both reliably grounded;

The upper end of the DC generating device (1) is electrically connected to the left end of the first high-voltage cable (4), the right end of the first high-voltage cable (4) is electrically connected to the left end of the current sensing device (5), and the current sensing device (5) The right end is electrically connected with the external lead-out port (7) of the grounding grid, the external lead-out port (7) of the grounding grid is electrically connected with the grounding grid (12), and the lower end of the DC generating device (1) is electrically connected with the upper end of the DC generating device controller (2), The lower end of the DC generator controller (2) is electrically connected with the core control device (13);

The soil test box (11) includes a first moisture sensor (9), a second moisture sensor (10), a grounding grid (12), and the first moisture sensor (9) and the second moisture sensor (10) are respectively associated with numerical values. The acquisition module (8) is electrically connected, and the numerical acquisition module (8) is electrically connected with the core control device (13);

The second step is to measure the soil moisture content and the DC response of the grounding grid of each section:

The specific moisture content in the soil is measured by the first moisture sensor (9) and the second moisture sensor (10) to obtain the comprehensive soil moisture content W _p ; Segmentation is performed, and the DC working current test is performed for each section of the grounding grid (12), and the specific steps include: controlling the DC generating device controller (2) through the core control device (13), and setting the DC generating device (1) The DC working voltage whose amplitude is _{UD is output, and the DC working current IsQ generated} by a certain section of grounding grid (12) under the DC working voltage is measured by the current sensing device (5), and transmitted to the data collection module (8) through the value acquisition module (8). The core control device (13) connects the current output port and the return port of the DC generating device (1) with the external lead wire ports of other segments of the grounding grid, and repeats the above-mentioned test steps to obtain a total of q groups of DC working current sampling data;

The third step is to obtain the soil risk assessment factor E _1Q of the grounding grid:

In the above formula, E _1Q is the first assessment factor for the soil risk of the Q group grounding grid, _{IsQ is the DC working current of the Q group ground grid, I zQ is} the standard value of the DC working current of the Q group ground grid, and T is Grounding grid running time, q is the total number of test groups;

Substitute the measured comprehensive soil moisture content W _p into the following formula to obtain the second evaluation factor E ₂ of the soil hazard characteristics of the grounding grid:

In the fourth step, based on the above steps, the comprehensive evaluation factor E of the soil risk of the grounding grid based on the moisture content is obtained:

Wherein S ₁ is the first benchmark weight factor, and S ₂ is the second benchmark weight factor;

When E ∈ (0, 0.14], it indicates that the soil risk of the grounding grid is outstanding, and the grounding system needs to be replaced or repaired immediately; when E ∈ (0.14, +∞), it indicates that the soil risk of the grounding grid is general and can be properly maintained on a regular basis.

Claims (1)

1. A grounding grid soil risk assessment method considering water content is characterized by comprising the following steps:

the method comprises the steps that firstly, a grounding grid soil risk testing platform is set up, and the platform comprises a direct current generating device (1), a direct current generating device controller (2), a direct current generating device grounding module (3), a first high-voltage cable (4), a current sensing device (5), a grounding grid external connection leading-out port (7), a numerical value collecting module (8), a first moisture sensor (9), a second moisture sensor (10), a soil test box (11), a grounding grid (12), a core control device (13) and a test box grounding module (33);

the direct current generating device grounding module (3) and the test box grounding module (33) are both reliably grounded;

the upper end of the direct current generating device (1) is electrically connected with the left end of a first high-voltage cable (4), the right end of the first high-voltage cable (4) is electrically connected with the left end of a current sensing device (5), the right end of the current sensing device (5) is electrically connected with an external grounding grid leading-out port (7), the external grounding grid leading-out port (7) is electrically connected with a grounding grid (12), the lower end of the direct current generating device (1) is electrically connected with the upper end of a direct current generating device controller (2), and the lower end of the direct current generating device controller (2) is electrically connected with a core control device (13);

the soil test box (11) comprises a first moisture sensor (9), a second moisture sensor (10) and a grounding grid (12), the first moisture sensor (9) and the second moisture sensor (10) are respectively and electrically connected with the numerical value acquisition module (8), and the numerical value acquisition module (8) is electrically connected with the core control device (13);

step two, measuring the water content of the soil and the direct current response of the grounding grid of each section:

measuring specific water content in the soil through a first water sensor (9) and a second water sensor (10) to obtain comprehensive soil water content W _p (ii) a Then, the grounding grid (12) is segmented according to a leading-out port (7) externally connected with the grounding grid, and direct current working current testing is carried out on each segment of the grounding grid (12), and the method specifically comprises the following steps: the core control device (13) controls the DC generator controller (2) and sets the output amplitude of the DC generator (1) to be U _D The direct current working voltage is measured by a current sensing device (5) to generate direct current working current I under the direct current working voltage of a certain section of grounding grid (12) _sQ Transmitting the data to a core control device (13) through a numerical value acquisition module (8), connecting a current output port and a backflow port of the direct current generating device (1) with external outgoing line ports of other sections of grounding networks, and repeating the test steps to obtain q groups of direct current working current sampling data;

thirdly, obtaining the direct current working current I _sQ Substituting the formula (1) to obtain a grounding grid soil risk evaluation factor E _1Q ：

In the above formula, E _1Q A first assessment factor for the soil risk of the group Q of the grounding nets, I _sQ For the direct operating current of the Q-th group of earthing networks, I _zQ The standard value of the direct current working current of the Q-th group grounding grid is set, T is the running time of the grounding grid, and Q is the total number of groups to be tested;

the measured comprehensive soil moisture content W _p Substituting the formula (2) into the formula (2) to obtain a second evaluation factor E of the soil hazard characteristics of the grounding grid ₂ ：

And fourthly, obtaining a comprehensive evaluation factor E of the soil risk of the grounding grid based on the water content based on the steps:

wherein S ₁ Is a first reference weight factor, S ₂ Is a second baseline weight factor;

when E belongs to (0, 0.14), the soil risk of the grounding grid is obvious and the grounding system needs to be replaced or overhauled immediately, and when E belongs to (0.14, infinity), the soil risk of the grounding grid is general and the grounding grid can be maintained properly and regularly.

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