KR100626813B1 - Scale Model Grounding Simulator for Ground Potential Rise Analysis - Google Patents

Abstract

The present invention is a hemispherical water tank containing a solution; A test grounding system installed in the tank but reduced in proportion to a shape, position, and size of a ground electrode of a real scale; A power supply device for applying AC power, which is a fault current, to the test ground system; A probe capable of horizontal movement on the hemispherical water tank but detecting a potential of the virtual earth surface flowing through the test ground system in contact with the solution contained in the water tank; And a control measuring device for measuring a ground voltage for each distance by measuring a horizontal movement control of the probe and a fault current flowing through the test ground system through a probe; By configuring the position control part of the potential detection probe and the automatic measurement system for automatically measuring the ground potential rise according to the current inflow, the shape of the equipotential surface generated when the current flows to the grounding system appears to be the same as the actual ground network. This provides a ground simulation system for earth potential rise analysis, which enables modeling and accurate analysis of earth potential rise due to fault current inflow.

Description

Scale Model Grounding Simulator for Ground Potential Rise Analysis             

1 is a schematic diagram illustrating a reduced model ground simulation system in an embodiment of the present invention.

2 is a circuit block diagram showing a control measurement apparatus according to an embodiment of the present invention.

3 shows the configuration of a simulated power grounding system according to an embodiment of the present invention.

4A and 4B show distribution ratios for the surface potential rise of the power ground according to the embodiment of the present invention.

5 illustrates a configuration of a grounding system according to an embodiment of the present invention.

6a and 6b show the surface potential rise distribution ratio in the independent ground according to an embodiment of the present invention.

Figure 7 shows the surface potential rise distribution ratio during bonding according to an embodiment of the present invention.

  Explanation of symbols on the main parts of the drawings

100: scale model ground simulator 110: water tank

120: test ground 130: power supply

140: external resistance 150: probe

200: control measuring device 210: frame

220: drive motor 230: motor control means

240: encoder 250: counter

260: Potentiometer 270: A / D Converter

280: controller (computer)

The present invention relates to a reduced model grounding simulator, and more particularly, to a ground simulation system for ground potential rise analysis for modeling a real scale grounding system at a predetermined ratio and automatically measuring ground potential rise according to a fault current.

As the scale and complexity of industrial plant facilities increase, there is a growing interest in designing a grounding system that combines safety and economic aspects.

In large scale power supply and signal grounding systems that require high soil resistivity or low resistance grounding systems, reticular grounding systems with many horizontal buried ground lines and vertical rods are used.

However, there are not many structural variables such as the optimal layout structure of the grounding system, that is, the depth of the horizontal buried ground line or the vertical rod, the grid spacing, the size of the ground electrode, and various characteristics according to the characteristics of the land such as the earth resistivity. Due to such a large number of variables, it is practically difficult to find the optimal layout structure by constructing a ground scale of a real scale.

As an alternative to the actual measurement, there is a numerical method using a calculator. However, a mesh grounding system requiring a ground resistance of 1 Ω or less requires a lot of calculation time to reduce the calculation error in the analysis.

This analytical method is very useful for evaluating grounding systems, but the modeling process is very complicated and the results of the analysis are difficult to verify accurately.

Therefore, in the present invention, by reducing the scale of the actual grounding system to a certain ratio, and by configuring the position control unit and automatic measurement system of the potential detection probe for automatically measuring the rise of the earth potential according to the fault current inflow, It is to provide a grounding simulation system for earth potential rise analysis that enables the modeling and accurate analysis of the earth potential rise due to the inflow of fault current by making the shape of the equipotential surface generated when current flows the same as the real ground network.

Technical means of the present invention for achieving the above object is a hemispherical water tank containing a solution; A test grounding system installed in the tank but reduced in proportion to a shape, position, and size of a ground electrode of a real scale; A power supply device for applying AC power, which is a fault current, to the test ground system; A probe capable of horizontal movement on the hemispherical water tank but detecting a potential of the virtual earth surface flowing through the test ground system in contact with the solution contained in the water tank; And a control measuring device for measuring a ground voltage for each distance by measuring a horizontal movement control of the probe and a fault current flowing through the test ground system through a probe.

Specifically, the tank or the inner surface of the tank is made of a conductive material, the solution contained in the tank is characterized by changing the conductivity by adjusting the concentration of the solution in accordance with the actual earth properties to be simulated.

In addition, the probe is coupled to the horizontal movement through the frame installed on the top of the tank.

The control measuring device includes: a probe driving motor for generating a left and right moving power of a probe on a predetermined frame; Motor control means for controlling forward / reverse rotation and rotational speed of the probe driving motor; An encoder for automatically measuring a moving distance of the probe; A counter for counting a signal output from the encoder and outputting a signal proportional to a moving distance; A potential meter indicating a potential of each point detected by the probe; An A / D converter receiving an analog signal corresponding to a moving distance and a ground potential of the probe from the counter and the potential meter, and converting the analog signal into a digital signal; And a controller which controls the motor control means and calculates and processes input data corresponding to the movement distance and earth potential of the probe output through the A / D converter according to a preset program to display the distance and earth potential. In addition, the encoder is installed in the probe driving motor is configured to detect the rotation angle of the motor, the controller is characterized in that to output the graph data corresponding to the ground potential for each distance in the plane coordinates.

Hereinafter, a detailed description of the present invention will be described with reference to the accompanying drawings.

1 is a view illustrating a scaled-down model ground simulator in an embodiment of the present invention, including a water tank 110, a test grounding system 120, a power supply device 130, a probe 150, and a control measuring device 200. Consists of

The water tank 110 is composed of a semi-spherical conductor containing a predetermined solution 115, the test grounding system 120 is installed in the water tank 110, a predetermined ratio corresponding to the shape, position and size of the ground electrode of the actual scale The power supply device 130 is configured to apply AC power, which is a fault current, to the test grounding system 120, and the probe 150 can move horizontally on the hemispherical water tank 110, but the water tank ( It is configured to detect the potential of the surface of the virtual earth flowing through the test ground 120 in contact with the solution 115 contained in the 110, the control measuring device 200 is the horizontal movement control of the probe 150 and the test ground It is configured to measure and display the ground voltage for each distance by measuring the fault current flowing through the system 120 through the probe 150.

In addition, the hemispherical water tank 110 or the inner surface of the water tank 110 is made of a conductive material, the solution 115 contained in the water tank 110 of the solution 115 according to the actual ground properties to be simulated The conductivity can be changed by adjusting the concentration.

In addition, a frame 210 is installed at an upper end of the water tank 110, and a probe 150 is coupled to the frame 210, and the probe 150 is framed under the control of the control measuring apparatus 200. 210 is configured to move horizontally.

2 is a circuit block diagram showing a control measuring apparatus according to an embodiment of the present invention, a probe driving motor 220, motor control means 230, encoder 240, counter 250, potential meter 260, It consists of an A / D converter 270 and a controller 280.

That is, the control measuring device 200 includes a probe driving motor 220 generating the left and right moving power of the probe 150 on a predetermined frame 210, and the forward / reverse rotation of the probe driving motor 220. Motor control means 230 for controlling the rotational speed, encoder 240 for automatically measuring the movement distance of the probe 150, and a signal proportional to the movement distance by counting the signal output from the encoder 240 A counter 250 for outputting a potential, a potentiometer 260 displaying a potential of each point detected through the probe 150, and a movement of the probe 150 from the counter 250 and the potentiometer 260. A / D converter 270 for receiving an analog signal corresponding to a distance and ground potential and converting the signal into a digital signal, and controlling the motor control means 230, but output the probe through the A / D converter 270 ( Preset input data corresponding to movement distance and ground potential of 150) The operation and processing in accordance with a program consists of a controller 280 to display the distance and the ground potential.

The encoder 240 is installed in the probe driving motor 220 and configured to detect a rotation angle of the motor 220. The controller 280 outputs graph data corresponding to earth potential for each distance in plane coordinates. Personal computers such as portable computers, notebooks, and desktops.

That is, the equipotential surface becomes a hemispherical surface when the observation point moves away from the electrode when the fault current flows into a finite length electrode buried on an even ground, and thus the electric field generated when the fault current flows into the test ground system 120, which is a reduced grounding model. In order to prevent distortion in the distribution is composed of a hemispherical water tank (110).

At this time, the inner surface of the water tank 110 or the water tank 110 should be made of a conductive material, to fill the electrolyte solution 115 in the water tank 110 to simulate the characteristics of the uniform earth, By varying the conductivity by adjusting the concentration, the soil resistivity of the actual soil can be simulated.

The test grounding system 120 manufactured by reducing the shape, size, and position of the actual grounding electrode in a semi-spherical water tank 110 configured as described above at a constant ratio corresponds to a distance from the surface of which the burial depth of the actual grounding system is reduced by the same ratio. Install at the position to be.

Subsequently, the power supply device 130 is capable of adjusting the applied current as an AC power source for applying a fault current to the test ground system 120, and applies insulation transformers T1 and T2 to electrically connect the primary side and the secondary side. The structure is separated by.

In addition, the external resistance 140 (Rext) refers to the resistance up to the hemisphere 110 to the infinity point, and depends on the size and earth resistivity of the hemisphere as shown in Equation 1 below.

However, r is the radius of the water tank 110, ρ is the earth resistivity.

The probe 150 is used to detect the potential of the ground surface, and to the movable auxiliary frame 210 of the same type as the conveyor installed on the tank 110 so as to measure the potential distribution according to the separation distance from the current application point. It is connected.

In order to automatically measure the earth potential rise distribution, a control system for controlling the position of the probe 150 and measuring the potential at each point is required, and the configuration thereof is shown in FIG.

The probe 150 is connected to the probe moving means (210, 220) is possible to adjust the position and is configured to adjust the moving direction and the moving speed by using the motor control means 230, the movement distance is automatically In order to measure by, the encoder 240 should be installed in combination with the drive motor 220.

The encoder 240 functions as a sensor for detecting the rotation of the motor 220, and outputs a DC voltage proportional to the moving distance through the counter 250 composed of a count and an integration circuit.

The potential of each point detected through the probe 150 is displayed through the potentiometer 260 and transmits a signal to the A / D converter 270.

Accordingly, the A / D converter 270 is simultaneously input a voltage signal corresponding to the moving distance and the voltage signal corresponding to the ground field, which are converted into digital signals and transmitted to the computer 280 through the port.

The computer 280 calculates and processes each input data through Labview software, and is configured to automatically output graph data having a distance on the x axis and a ground potential on the y axis.

The automatic control system for position control and moving distance measurement adjusts the position of the potential detection probe 150 connected to the probe moving means 210 or 220 through the speed control of the position control motor 220 as shown in FIG. The encoder 240 detects the rotation angle of the motor 220, that is, the movement distance of the probe 150, and converts it to the movement distance through the counter 250 and displays a DC voltage linearly proportional to the distance. Output

Looking at the operation of the ground ground simulation system configured as described above through the experimental example.

First, the ground was simulated with groundwater having a resistivity of 39.1 Ω · m, and the external resistance 140 (Rext) refers to the resistance to the hemispherical water tank 110 against infinity, and the size and earth resistivity of the water tank 110. 6.22Ω was applied in this experiment.

The test grounding system 120 includes, for example, a power grounding system for grounding an AC 220V power supply and a signal grounding system for grounding a DC power supply. Is shown in Table 1.

Earth meter Grid size interval Ground conductor radius Buried depth Power Ground 32m × 32m 4m 5.25mm 0.5m Signal ground 16m × 16m 4m 5.25mm 0.5m

However, the power grounding system and the signal grounding system of the test grounding system 120 actually applied were 0.32m × 0.32m and 0.16m × 0.16m, respectively, with a mesh electrode structure (grid spacing 0.04m) installed at a depth of 5 mm from the surface.

Here, the radius of the grounding conductor is 10: 1 scale for manufacturing reasons.

Surface potential measurement probe 150 is automatically adjusted through the probe moving means (210, 220), the output voltage is automatically measured the potential (y axis) relative to the position (x axis) by the Labview program.

The simulated ground system is shown in FIG. 3, and when the current of 1A is applied to the center of the ground electrode, the potential rise distribution of the surface was measured in the transverse direction (a-d) and the diagonal direction (e).

Fig. 4A shows the distribution ratio for the surface potential rise of the a to d direction (the transverse direction), that is, the power ground. As the distance increases at the point of application of the current, the potential rise gradually decreases and decreases rapidly at the point away from the network electrode.

4b compares the results of the potential rise distribution measurement and the numerical analysis of the power ground in the diagonal direction.

Although the voltage drop between the meshes was measured slightly more slowly than the analysis result, this is because the gap between the test grounding probe 120 and the probe 150 for inspection has some errors due to the installation problem, and the overall aspect is almost similar. appear.

Similar trends were observed for the signal grounding system, and the ground resistances of the power grounding system and the signal grounding system simulated at single grounding are shown in Table 2. The ground resistances were 53.6Ω and 105.8Ω, respectively, which were very close to the results of the analysis.

division Earth resistance [Ω] Measures Analysis value Power Ground 53.6 55.2 Signal ground 105.8 112.6

In order to measure the potential rise distribution of the independent ground and the common ground, a grounding system was constructed using two independent grounding systems as shown in FIG. 5.

Table 3 shows the ground resistance measurement values according to the configuration of the ground meter. In each case, the ground resistance of the independent ground is almost the same as that of the single power ground, which is considered to have a dominant influence on the power ground system of a relatively large size compared to the signal ground.

When two grounding systems are bonded, the grounding resistance is 42Ω, which is lower than that of independent grounding.

division Earth resistance [Ω] Measures Analysis value Independent Ground 53.6 55.2 Common ground (bonding) 40.6 40.9

6A and 6B show the measurement and analysis of the potential rise distribution in the a and b directions at the independent grounding.

When the current of 1A is applied to the center of the power grounding system, the potential rise decreases with the increase of the separation distance, and then some distortion occurs at the point where the signal grounding system is located.The measurement result is almost the same as the analysis result. Indicated.

7 shows the potential rise distribution characteristic when two grounding systems are bonded and grounded together.

In FIG. 5, the potential of the signal grounding system is increased by about 90% when the points 1-c are bonded to each other, but the potential difference with the power grounding system is within 5%.

Although the measured value of the potential rise was slightly lower than that of the ground electrode in comparison with the calculated result, the overall trend was similar.

Here, it can be seen that the independent grounding is advantageous if the potential rise of the signal grounding system is merely viewed from the ground potential rise.

However, if the AC power supply of the communication equipment is connected to the power ground during independent grounding and the DC power supply, shield wire, or the enclosure of the communication equipment is connected to the communication grounding system, a large potential difference between the two grounding systems may cause damage to the equipment. have.

Therefore, bonding two grounding systems not only reduces grounding resistance, but also is effective in preventing accidents by equipotentializing.

In order to verify the effectiveness of the miniature grounding system, a small simulated grounding system was constructed to characterize the grounding system.

First, the surface ground potential rise was measured for the reticulated grounding system simulating the grounding of the power supply and the signal ground using the reduced simulation grounding system. The measurement results for the surface earth potential rise and the simulation results by numerical analysis showed similar patterns, which confirmed the effectiveness of the reduced grounding system.

In addition, the potential rise distributions of the independent grounding and the common grounding by bonding were analyzed. Through this, the potential difference between the two grounding systems was reduced and the accident prevention was effective.

The reduced model ground simulation system can be used to design and characterize grounding systems of various structures and to analyze the effects of earth potential rise.

As described above, the present invention is a scaled-down model ground simulator for analyzing the ground potential rise characteristics of a grounding system, and experiments by reducing the actual grounding system to a certain ratio, thereby realizing various types of grounding that cannot be practically analyzed for a real-scale system. This has the advantage of enabling characterization of the system. In other words, it is possible to experimentally analyze the change of the grounding characteristics according to the change of the shape, size and burial depth of the grounding electrode for various types of reticulated grounding systems combined with horizontal conductors and ground rods.

In addition, when several grounding systems such as power grounding and signal grounding are mixed, they can be used for characterization by separating or bonding them, and as a result, they can be used as an evaluation tool for grounding systems to design an optimal grounding system economically and effectively. There is an advantage to that.

Claims (7)

Hemispherical water bath containing the solution; A test grounding system installed in the tank but reduced in proportion to a shape, position, and size of a ground electrode of a real scale; A power supply device for applying AC power, which is a fault current, to the test ground system; A probe capable of horizontal movement on the hemispherical water tank but detecting a potential of the virtual earth surface flowing through the test ground system in contact with the solution contained in the water tank; And A grounding simulation system for ground potential rise analysis, comprising: a control measuring device for measuring a ground voltage for each distance by measuring a horizontal movement control of the probe and a fault current flowing through the test ground system through a probe. The method according to claim 1, Ground simulation system for ground potential rise analysis, characterized in that the tank or the inner surface of the tank is made of a conductive material. The method according to claim 1, The ground simulation system for ground potential rise analysis, characterized in that the solution contained in the tank changes the conductivity by adjusting the concentration of the solution in accordance with the actual ground properties to be simulated. The method according to claim 1, The probe is ground simulation system for ground potential rise analysis, characterized in that coupled to the horizontal movement through the frame installed on the top of the tank. The method according to claim 1, The control measuring device includes: a probe driving motor for generating a left and right moving power of a probe on a predetermined frame; Motor control means for controlling forward / reverse rotation and rotational speed of the probe driving motor; An encoder for automatically measuring a moving distance of the probe; A counter for counting a signal output from the encoder and outputting a signal proportional to a moving distance; A potential meter indicating a potential of each point detected by the probe; An A / D converter receiving an analog signal corresponding to a moving distance and a ground potential of the probe from the counter and the potential meter, and converting the analog signal into a digital signal; And a controller that controls the motor control means and calculates and processes input data corresponding to the movement distance and ground potential of the probe output through the A / D converter according to a preset program to display the distance and ground potential. Ground simulation system for earth potential rise analysis. The method according to claim 5, The encoder is installed in the probe driving motor ground simulation system for ground potential rise analysis, characterized in that configured to detect the rotation angle of the motor. The method according to claim 5, The controller is a ground simulation system for ground potential rise analysis, characterized in that for outputting the graph data corresponding to the ground potential for each distance in the plane coordinates.

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