Impacts of Diverting Potential Difference on Armored Cables in Substations

2014 ◽  
Vol 986-987 ◽  
pp. 931-935
Author(s):  
Li Chen
Keyword(s):  
Dielectric Breakdown ◽  
Simulation Software ◽  
Potential Difference ◽  
Insulation Material ◽  
Grid Simulation ◽  
Transient Electromagnetic ◽  
Grounding Grid ◽  
Large Current ◽  
Electrical Tree ◽  
Grounding Grids

To reduce the interference on communication equipments caused by transient electromagnetic field of switching operation, the shields of cables are connected to grounding grid on both sides in the substations grounding designs. However, when the substation is stroke by lightning or shorted, the huge potential difference called diverting potential difference between the cable core and the shield is generated, which can easily destroy insulation of cables, even producing electrical tree or dielectric breakdown in insulation material. Moreover, the large current flowing through the shield of cables will cause personnel accidents and equipment damages. In this paper, the electric model of cables is established using grounding grid simulation software—CEDGS. The way diverting potential difference changes influenced by grounding grids, soil and other parameters is analyzed. Measures to reduce diverting potential difference are proposed for providing a theoretical basis of construction in practice.

scholarly journals Diagnosis for Conductor Breaks of Grounding Grids Based on the Wire Loop Method of the Transient Electromagnetic Method

2019 ◽  
Vol 2019 ◽  
pp. 1-11 ◽  
Author(s):  
Shengbao Yu ◽  
Guanliang Dong ◽  
Nannan Liu ◽  
Xiyang Liu ◽  
Chang Xu ◽  
...  
Keyword(s):  
Topological Structure ◽  
Electromagnetic Response ◽  
Height Difference ◽  
Measuring Point ◽  
Wire Loop ◽  
Loop Method ◽  
Transient Electromagnetic ◽  
Grounding Grid ◽  
Grounding Grids ◽  
The Wire

The wire loop method of the transient electromagnetic (TEM) method is used to nondestructively detect conductor breaks of grounding grid. For this purpose, grounding grids serve as an underground wire loop, and the measuring points are arranged on the ground. At each measuring point, a receiving loop is employed to detect the electromagnetic response generated by transmitting the current of the transmitting loop. Conductor breaks can be diagnosed by analyzing the slices of the electromagnetic response. We study the effect of loop size and height difference through the simulation of an intact 2×2 grounding grid, confirming that it is easier to obtain the topological structure using a small transmitting loop and a small height difference. Furthermore, simulations of an intact 4×4 grounding grid and grids with different locations of conductor breaks are also conducted with a small transmitting loop. It is easy to distinguish the topological structure of the grounding grid and the locations of conductor breaks. Finally, the detection method is applied experimentally. The experimental results confirm that the proposed method is an effective technique for conductor break diagnosis.

scholarly journals Research on grounding grid corrosion classification method based on convolutional neural network

2018 ◽  
Vol 160 ◽  
pp. 01008
Author(s):  
Jingyi Du ◽  
Liqian Yan ◽  
Haixia Wang ◽  
Qiong Huang
Keyword(s):  
Neural Network ◽  
Classification Performance ◽  
Detection Methods ◽  
Svm Classifier ◽  
Image Method ◽  
Grid Simulation ◽  
Grounding Grid ◽  
Grounding Grids ◽  
Improved Model ◽  
Better Than

Aiming at the problem that the traditional detection methods can not accurately classify the corrosion degree of grounding grids. The corrosion image is taken as the research object, the convolution neural network is used as the algorithm firstly to classify the corrosion degree. Firstly, the corrosion simulation experiment was carried out, and the sample library was established by using the corrosion image collected in different stages. Then, according to the LeNet-5 model, the traditional CNN and improved CNN models were designed for corrosion classification of grounding grid. Simulation experiments were carried out in the preprocessed samples. Finally, the experimental results of Soft-max and SVM classifier are compared and analyzed. The results show: the classification results of the two models were better than those of the original samples, and the classification performance of SVM is better than that of Soft-max. The improved model can improve classification accuracy. This study fills the blank of detecting the corrosion degree of grounding grid by image method, and it is significant to quickly grasp the corrosion degree to avoid faults or accidents.

scholarly journals Application of the Gaussian Mixture Model to Classify Stages of Electrical Tree Growth in Epoxy Resin

Sensors ◽  
2021 ◽  
Vol 21 (7) ◽  
pp. 2562
Author(s):  
Abdullahi Abubakar Mas’ud ◽  
Arunachalam Sundaram ◽  
Jorge Alfredo Ardila-Rey ◽  
Roger Schurch ◽  
Firdaus Muhammad-Sukki ◽  
...  
Keyword(s):  
Epoxy Resin ◽  
Gaussian Mixture Model ◽  
Mixture Model ◽  
Tree Growth ◽  
Asset Management ◽  
Gaussian Mixture ◽  
Growth Stages ◽  
Insulation Material ◽  
Electrical Tree ◽  
Electrical Trees

In high-voltage (HV) insulation, electrical trees are an important degradation phenomenon strongly linked to partial discharge (PD) activity. Their initiation and development have attracted the attention of the research community and better understanding and characterization of the phenomenon are needed. They are very damaging and develop through the insulation material forming a discharge conduction path. Therefore, it is important to adequately measure and characterize tree growth before it can lead to complete failure of the system. In this paper, the Gaussian mixture model (GMM) has been applied to cluster and classify the different growth stages of electrical trees in epoxy resin insulation. First, tree growth experiments were conducted, and PD data captured from the initial to breakdown stage of the tree growth in epoxy resin insulation. Second, the GMM was applied to categorize the different electrical tree stages into clusters. The results show that PD dynamics vary with different stress voltages and tree growth stages. The electrical tree patterns with shorter breakdown times had identical clusters throughout the degradation stages. The breakdown time can be a key factor in determining the degradation levels of PD patterns emanating from trees in epoxy resin. This is important in order to determine the severity of electrical treeing degradation, and, therefore, to perform efficient asset management. The novelty of the work presented in this paper is that for the first time the GMM has been applied for electrical tree growth classification and the optimal values for the hyperparameters, i.e., the number of clusters and the appropriate covariance structure, have been determined for the different electrical tree clusters.

scholarly journals Controlled Switching of the T402 Transformer in the Križovany 400kV Substation

2010 ◽  
Vol 61 (1) ◽  
pp. 11-19
Author(s):  
František Janíček ◽  
Martin Mucha ◽  
Karol Česnek ◽  
Jozef Kováčik
Keyword(s):  
Control Unit ◽  
Simulation Software ◽  
Transient Phenomena ◽  
Controlled Switching ◽  
Transient Electromagnetic ◽  
Statistical Frequency

Controlled Switching of the T402 Transformer in the Križovany 400kV Substation The paper deals with simulating the circumstances of switching surge and trigger current at switching-in of the T402 autotransformer recently installed in Križovany, with the tests conducted by means of ATP (Alternative Transient Program) simulation software for simulating transient electromagnetic phenomena. The target has been to determine temporal curves for the most critical surge instances against earth and between the phases and the curves for trigger current with and without surge limiters connected, and to determine by means of simulations the size and statistical frequency of switching surges and based on a controlled switching simulation, to describe the elimination of transient phenomena during the process and in reference to the simulations and to operating manual for the PSD02 Siemens control unit, suggest the required configuration settings for the unit.

Configuration Detection of Substation Grounding Grid Using Transient Electromagnetic Method

2017 ◽  
Vol 64 (8) ◽  
pp. 6475-6483 ◽  
Author(s):  
Cigong Yu ◽  
Zhihong Fu ◽  
Gaolin Wu ◽  
Liuyuan Zhou ◽  
Xuegui Zhu ◽  
...  
Keyword(s):  
Electromagnetic Method ◽  
Transient Electromagnetic Method ◽  
Transient Electromagnetic ◽  
Grounding Grid

Comparative Characterisation of CNS/Epoxy and BN/Epoxy Nanodielectrics Using Electrical Tree PD Measurements and Atomic Force Microscopy

2020 ◽  
Vol 48 ◽  
pp. 24-37
Author(s):  
Andrew M. Hank ◽  
Cuthbert Nyamupangedengu ◽  
Bridget Mutuma ◽  
Hu Li ◽  
Neil John Coville ◽  
...  
Keyword(s):  
The Body ◽  
Time To Failure ◽  
Insulation Material ◽  
Carbon Nanospheres ◽  
Mechanical Stiffness ◽  
Force Microscopy ◽  
Body Of Knowledge ◽  
Atomic Force ◽  
Electrical Tree ◽  
Evolution Characteristics

This paper contributes to the body of knowledge on the efforts to develop nanodielectrics as the next generation of insulation material. The time-to-failure under electrical tree-induced degradation of 1.09-1.35 vol.% hexagonal BN/Epoxy was found to be 3 times longer than in clean epoxy. For 0.31-0.33 vol.% CNS/Epoxy the time-to-failure was 24 times longer than the clean epoxy. The electrical treeing partial discharge behaviour in the BN/Epoxy and CNS/Epoxy showed distinct time-evolution characteristics different from those in the clean epoxy. The improved electrical tree endurance in BN/Epoxy relative to the clean epoxy can be attributed to increased mechanical stiffness. The superiority of the CNS/Epoxy as a nanodielectric is notable. The effect is suggested to be due to the electron affinity properties of the carbon nanospheres at appropriate dispersion levels.

scholarly journals Detecting Grounding Grid Orientation: Transient Electromagnetic Approach

2019 ◽  
Vol 9 (24) ◽  
pp. 5270 ◽  
Author(s):  
Aamir Qamar ◽  
Inzamam Ul Haq ◽  
Majed Alhaisoni ◽  
Nadia Nawaz Qadri
Keyword(s):  
Eddy Currents ◽  
Comsol Multiphysics ◽  
Electromagnetic Environment ◽  
Diagonal Branch ◽  
Transient Electromagnetic ◽  
Grounding Grid ◽  
The Status ◽  
Mesh Spacing ◽  
Grid Orientation ◽  
Inversion Calculation

The configuration is essential to diagnose the status of the grounding grid, but the orientation of the unknown grounding grid is ultimately required to diagnose its configuration explicitly. This paper presents a transient electromagnetic method (TEM) to determine grounding grid orientation without excavation. Unlike the existing pathological solutions, TEM does not enhance the surrounding electromagnetic environment. A secondary magnetic field as a consequence of induced eddy currents is subjected to inversion calculation. The orientation of the grounding grid is diagnosed from the equivalent resistivity distribution against the circle perimeter. High equivalent resistivity at a point on the circle implies the grounding grid conductor and vice versa. Furthermore, various mesh configurations including the presence of a diagonal branch and unequal mesh spacing are taken into account. Simulations are performed using COMSOL Multiphysics and MATLAB to verify the usefulness of the proposed method.

Cathodic Protection of Grounding Grids

2018 ◽  
pp. 248-286
Keyword(s):  
Cathodic Protection ◽  
Galvanic Corrosion ◽  
Steel Corrosion ◽  
Uniform Corrosion ◽  
Grounding System ◽  
Grounding Grid ◽  
Grounding Grids ◽  
Corrosion Pitting ◽  
Impressed Current ◽  
Cathodic Protection System

This chapter contains the corrosion theory of grounding electrodes and basic electrochemistry in corrosion reactions. It contains also the forms of substation grounding grid corrosion (uniform corrosion, pitting corrosion, galvanic corrosion, microbial influenced corrosion), survey on corrosion rate of substation grounding grid, copper and steel corrosion rates, corrosion protection methods (coating, cathodic protection [CP]). The chapter contains also the methods of applying cathodic protection in grounding grids, anode selection, anode spacing, and impressed current in the grounding grid cathodic protection. Finally it contains the required information for design grounding system cathodic protection and sacrificial anode (galvanic) cathodic protection system design steps.

scholarly journals Derivative Method Based Orientation Detection of Substation Grounding Grid

Energies ◽  
2018 ◽  
Vol 11 (7) ◽  
pp. 1873 ◽  
Author(s):  
Aamir Qamar ◽  
Muhammad Umair ◽  
Fan Yang ◽  
Muhammad Uzair ◽  
Zeeshan Kaleem
Keyword(s):  
Magnetic Flux ◽  
Flux Density ◽  
Critical Parameters ◽  
Magnetic Flux Density ◽  
Main Peak ◽  
Diagonal Branch ◽  
Grounding Grid ◽  
Derivative Method ◽  
Grounding Grids ◽  
Orientation Detection

The grounding grid is a key part of substation protection, which provides safety to personnel and equipment under normal as well as fault conditions. Currently, the topology of a grounding grid is determined by assuming that its orientation is parallel to the plane of earth. However, in practical scenarios, the assumed orientation may not coincide with the actual orientation of the grounding grid. Hence, currently employed methods for topology detection fails to produce the desired results. Therefore, accurate detection of grounding grid orientation is mandatory for measuring its topology accurately. In this paper, we propose a derivative method for orientation detection of grounding grid in high voltage substations. The proposed method is applicable to both equally and unequally spaced grounding grids. Furthermore, our method can also determine the orientation of grounding grid in the challenging case when a diagonal branch is present in the mesh. The proposed method is based on the fact that the distribution of magnetic flux density is perpendicular to the surface of the earth when a current is injected into the grid through a vertical conductor. Taking the third order derivative of the magnetic flux density, the main peak coinciding with the position of underground conductor is accurately obtained. Thus, the main peak describes the orientation of buried conductor of grounding grid. Simulations are performed using Comsol Multiphysics 5.0 to demonstrate the accuracy of the proposed method. Our results demonstrate that the proposed method calculate the orientation of grounding grid with high accuracy. We also investigate the effect of varying critical parameters of our method.

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