Distribution network grounding current diffusion hazard assessment method based on different ponding depths

Abstract

The invention, which belongs to the technical field of distribution network engineering protection, discloses a distribution network grounding current diffusion hazard assessment method based on different accumulated water depths, mainly comprising a power supply module, a disc electrode, a line module, a metal hemispherical shell, an accumulated water layer, a grounding module, an integrated module, a connecting line, an insulating fence and the like. A distribution network grounding current diffusion hazard assessment test platform is built, distribution network grounding current diffusion tests under different accumulated water thicknesses are carried out, and the accumulated water layer depth is recorded, so that a distribution network grounding current diffusion hazard assessment factor analytic expression is obtained. The distribution network grounding current diffusion hazard assessment test platform established by the invention can effectively test distribution network grounding fault current diffusion under different ponding depths, can obtain distribution network grounding current diffusion hazard assessment factors based on different ponding depths, and provides theoretical support for distribution network project current diffusion diversification safety assessment and protection decision under complex working conditions.

Description

Technical Field

[0001] The present invention belongs to the technical field of distribution network engineering protection, and in particular relates to a distribution network grounding scattered current hazard assessment method based on different water accumulation depths. Background Art

[0002] "Digitalization and intelligence" are important driving forces supporting the development of the "dual carbon" goals. With the continuous development and growth of new power systems, the construction of smart distribution network projects has also exploded. The previous situation of "focusing on the main network and neglecting the distribution network" will be further improved accordingly. At the same time, it will also face considerable challenges, especially when facing a surge in the number of power generation and energy-consuming equipment, a large number of differentiated terminals pouring into the power grid, and mixed high and low current, DC, and AC. Fault stray currents, equipment leakage currents, and induced currents will enter the ground, endangering personal safety. It is necessary to focus on the research on the hazard assessment of grounding stray currents in the distribution network to ensure the safe and stable operation of the smart distribution network system.

[0003] Lightning protection for distribution network lines in many parts of my country remains incomplete. Furthermore, my country is located in a region prone to thunderstorms, making distribution network grounding and current leakage accidents more likely to occur. Disconnected grounding faults are often overlooked in distribution network line protection, leading to prolonged energized system operation. Long rainy seasons or short, torrential downpours can cause waterlogging on urban and rural roads. The depth of this waterlogging significantly impacts the dissipation of fault currents, and also impacts safety decisions for nearby personnel. However, little research has been conducted on the risk of grounding and current leakage in distribution network systems under varying waterlogging depths, and there is a lack of methods for assessing the hazard of grounding and current leakage in distribution network systems under varying waterlogging depths. To better improve grounding safety protection design in distribution network projects, ensure the overall stable operation of intelligent distribution network systems, and analyze potential electric shock hazards in the surrounding environment, it is urgently necessary to develop a method for assessing the hazard of grounding and current leakage in distribution network systems under varying waterlogging depths. This method can provide theoretical and scientific reference for the diversified safety assessment of current leakage in distribution network projects under complex operating conditions. Summary of the Invention

[0004] The purpose of the present invention is to address the deficiencies of the prior art and to provide a method for evaluating the hazard of grounding current leakage in distribution networks at different water depths.

[0005] To achieve the above object, the technical solution adopted by the present invention is as follows: The distribution network grounding stray current hazard assessment method based on different water depths includes the following steps: The first step is to build a distribution network grounding and scattered current hazard assessment test platform, which includes a distribution network simulation platform and a water accumulation simulation platform; the distribution network simulation platform includes a distribution network power module, which is connected to at least one line module via a source connection line module, and the same phase line of each line module is connected together and connected to the water accumulation simulation platform via the first phase line; The water accumulation simulation platform includes a metal hemispherical shell, a large ground layer is set in the metal hemispherical shell, a water accumulation layer is set above the large ground layer, and a disk electrode 1, a disk electrode 2 and a bare wire are set in the water accumulation layer; wherein an integrated module is connected between the disk electrode 1 and the disk electrode 2, and the bare wire is connected to the broken part of the first phase line through the connecting wire 1; Step 2: Conduct grounding current dissipation tests on distribution networks at different water depths: By injecting fresh water into the metal hemispherical shell and recording the depth of the water layer, the electrical quantity at the depth of the water layer is measured by the integrated module, and the above test steps are repeated after a fixed time interval, a total of j Distribution network grounding scattered current sampling data; Step 3: Calculate the distribution network grounding current hazard assessment factor Y Zh : In the above formula, Y Zh is the distribution network grounding stray current hazard assessment factor, Z is the human body impedance, h j For the j The depth of the water layer during the first test, I w The current threshold that is safe for the human body to tolerate; The fourth step is to conduct a distribution network grounding stray current hazard assessment taking into account different water accumulation thicknesses.

[0006] An insulating enclosure 1 and an insulating enclosure 2 are respectively arranged on both sides of the metal hemispherical shell, the insulating enclosure 1 and the insulating enclosure 2 are marked with scales, and the accumulated water layer is located within the insulating enclosure 1 and the insulating enclosure 2.

[0007] The circuit modules include a first circuit module, a second circuit module, ... a Kth circuit module, where K is an integer greater than or equal to 1.

[0008] The integrated module integrates a human body equivalent circuit model and a current acquisition device. One end of the integrated module is electrically connected to the disk electrode 1 through the connecting line 2, and the other end of the integrated module is electrically connected to the disk electrode 2 through the connecting line 3.

[0009] The distance between the first and second disk electrodes is fixed at 1 m.

[0010] The volume of the metal hemispherical shell is much larger than that of the two disc electrodes. The metal hemispherical shell is filled with conventional soil and compacted into a hemispherical soil layer. The water accumulation layer is located above the hemispherical soil layer, and the depth of the water accumulation layer is less than or equal to 1m.

[0011] Compared with the prior art, the present invention has the following beneficial effects: 1) The grounding stray current hazard assessment test platform constructed by the present invention can effectively test the grounding stray current of distribution network faults at different water depths, providing a basis for the analytical characterization of assessment factors; 2) The evaluation method of the present invention can obtain the distribution network grounding scattered flow hazard assessment factor based on different water accumulation depths and can be applied to scattered flow risk assessment. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 It is a schematic diagram of the overall structure of the distribution network grounding scattered current hazard assessment test platform when the present invention is used. DETAILED DESCRIPTION

[0013] The present invention will be described in further detail below with reference to the accompanying drawings.

[0014] Depend on Figure 1 It can be seen that the method for evaluating the hazard of grounding current in distribution networks at different water depths provided by the present invention includes the following steps: The first step is to build a distribution network grounding and scattered current hazard assessment test platform, which includes a distribution network simulation platform and a water accumulation simulation platform. The distribution network simulation platform includes a distribution network power module 1, which is connected to at least one line module via a source connection line module 19. The same phase line of each line module is connected together and connected to the water accumulation simulation platform via a first phase line 18. In other words, the first phase line 18 belongs to a phase line in the line module 2 and can be phase A, phase B, or phase C. The water accumulation simulation platform includes a metal hemispherical shell 14, a large stratum is set inside the metal hemispherical shell 14, a water accumulation layer 15 is set above the large stratum, and a disk electrode 19, a disk electrode 2 10 and a bare wire 11 are set in the water accumulation layer 15; wherein, an integrated module 6 is connected between the disk electrode 19 and the disk electrode 2 10, and the bare wire 11 is connected to the broken part of the first phase line 18 through the connecting line 15.

[0015] It should be noted that the bottom of the metal hemispherical shell 14 is connected to the grounding module 16 via a connecting line 9 17.

[0016] Preferably, an insulating enclosure 12 and an insulating enclosure 2 13 are respectively provided on both sides of the metal hemispherical shell 14 , the insulating enclosure 12 and the insulating enclosure 2 13 are marked with scales, and the water accumulation layer 15 is located within the insulating enclosure 12 and the insulating enclosure 2 13 .

[0017] Furthermore, the circuit module includes a first circuit module 2 , a second circuit module 3 . . . a Kth circuit module 4 , where K is an integer greater than or equal to 1.

[0018] Furthermore, the integrated module 6 integrates a human body equivalent circuit model and a current acquisition device. One end of the integrated module 6 is electrically connected to the disk electrode 1 9 via the second connecting wire 7, and the other end of the integrated module 6 is electrically connected to the disk electrode 2 10 via the third connecting wire 8. It should be noted that the human body equivalent circuit model is a prior art, and the human body impedance is obtained using this model.

[0019] More preferably, the distance between the disk electrode 1 9 and the disk electrode 2 10 is fixed at 1 m, and the disk electrode 1 9 , the disk electrode 2 10 and the bare wire 11 are all located in the water accumulation layer 15 .

[0020] Furthermore, the volume of the metal hemispherical shell 14 is much larger than the volume of the two disc electrodes. The metal hemispherical shell 14 is filled with conventional soil and compacted into a hemispherical soil layer. The water accumulation layer 15 is located above the hemispherical soil layer, and the depth of the water accumulation layer 15 is controlled within 1m.

[0021] The second step is to conduct a distribution network grounding current test under different water depths: by injecting fresh water into the metal hemispherical shell 14 and recording the depth of the water layer 15, the electrical quantity at the depth of the water layer is measured by the integrated module 6. The electrical quantity is the current measured by the integrated module 6. Repeat the above test steps after a fixed interval, and get a total of j Distribution network grounding scattered current sampling data.

[0022] Step 3: Calculate the distribution network grounding current hazard assessment factor Y Zh : In the above formula, Y Zh is the distribution network grounding stray current hazard assessment factor, Z is the human body impedance, h j For the j The depth of the water layer during the first test, I w The current threshold that is safe for the human body to tolerate; The relationship between the thickness of the water layer in the formula and the electrical quantity measured in integrated module 6 is obtained by polynomial fitting. Then, the current measured in integrated module 6 (i.e., the current flowing through the human body) is expressed by a function with the thickness of the water layer as a variable. It is compared with the safe tolerance current of the human body, and the influence of human body impedance on the potential difference of the distribution network grounding and scattered current is introduced. Finally, the expression of the distribution network grounding and scattered current hazard assessment factor is obtained.

[0023] The fourth step is to conduct a distribution network grounding stray current hazard assessment based on different water depths. The larger the assessment factor, the greater the risk of grounding stray current to the human body. The distribution network grounding stray current hazard assessment factor includes the ratio of the current flowing through the human body to the human body's safe tolerance current. If the current flowing through the human body exceeds the human body's tolerance current, it is dangerous. It also includes the human body impedance factor, which is positively correlated with the stray current potential difference between the human feet.

Claims

1. A method for evaluating the hazard of grounding current in distribution networks at different water depths, characterized in that: The following steps are involved: The first step is to build a distribution network grounding scattered current hazard assessment test platform, which includes a distribution network simulation platform and a water accumulation simulation platform; the distribution network simulation platform includes a distribution network power module (1), the distribution network power module (1) is connected to at least one line module through a source connection line module (19), the same phase line of each line module is connected together, and is connected to the water accumulation simulation platform through a first phase line (18); The water accumulation simulation platform includes a metal hemispherical shell (14), a large earth layer is arranged in the metal hemispherical shell (14), a water accumulation layer (15) is arranged above the large earth layer, and a disk electrode 1 (9), a disk electrode 2 (10) and a bare wire (11) are arranged in the water accumulation layer (15); wherein, an integrated module (6) is connected between the disk electrode 1 (9) and the disk electrode 2 (10), and the bare wire (11) is connected to the broken part of the first phase line (18) through the connecting line 1 (5); Step 2: Conduct grounding current dissipation tests on distribution networks at different water depths: By injecting fresh water into the metal hemispherical shell (14), recording the depth of the water layer, and measuring the electrical quantity at the depth of the water layer through the integrated module (6), repeating the above test steps after a fixed time interval, a total of j Distribution network grounding scattered current sampling data; Step 3: Calculate the distribution network grounding current hazard assessment factor Y Zh : In the above formula, Y Zh is the distribution network grounding stray current hazard assessment factor, Z is the human body impedance, h j For the j The depth of the water layer during the first test, I w The current threshold that is safe for the human body to tolerate; The fourth step is to conduct a distribution network grounding stray current hazard assessment taking into account different water accumulation thicknesses.

2. The method for evaluating the hazard of grounding current in distribution networks at different water depths according to claim 1 is characterized in that: An insulating enclosure 1 (12) and an insulating enclosure 2 (13) are respectively provided on both sides of the metal hemispherical shell (14), and scales are marked on the insulating enclosure 1 (12) and the insulating enclosure 2 (13). The water accumulation layer (15) is located within the insulating enclosure 1 (12) and the insulating enclosure 2 (13).

3. The method for evaluating the hazard of grounding current in distribution networks at different water depths according to claim 1 is characterized in that: The circuit module comprises a first circuit module (2), a second circuit module (3) ... a Kth circuit module (4), wherein K is an integer greater than or equal to 1.

4. The method for evaluating the hazard of grounding current in distribution networks at different water depths according to claim 1 is characterized in that: The integrated module (6) integrates a human body equivalent circuit model and a current acquisition device. One end of the integrated module (6) is electrically connected to the disk electrode one (9) via the connecting line two (7), and the other end of the integrated module (6) is electrically connected to the disk electrode two (10) via the connecting line three (8).

5. The method for evaluating the hazard of grounding current in distribution networks at different water depths according to claim 4 is characterized in that: The distance between the disk electrode 1 (9) and the disk electrode 2 (10) is fixed at 1 m.

6. The method for evaluating the hazard of grounding current in distribution networks at different water depths according to claim 1 is characterized in that: The volume of the metal hemispherical shell (14) is much larger than the volume of the two disc electrodes. The metal hemispherical shell (14) is filled with conventional soil and compacted into a hemispherical soil layer. The water accumulation layer (15) is located above the hemispherical soil layer. The depth of the water accumulation layer (15) is less than or equal to 1m.

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