Research on Distribution Characteristics of DC Potential Near the UHVDC Grounding Electrode

Hao, Jianhong; Teng, Wanyi; Zhang, Yuguan; Liu, Wenlin

doi:10.1109/access.2020.3007094

Cited by 10 publications

(6 citation statements)

References 12 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The inversion of one-dimensional soil parameters in the frequency domain with considering multilayered soil model based on simulated annealing algorithm is proposed in [20]. In recent years, researchers have persistently explored the horizontally layered soil model and made advancements in its measurement process, forward modeling, and inversion optimization [21], [22], [23], [24], [25], [26], [27].…”

Section: Introductionmentioning

confidence: 99%

Optimal Inversion Method for Composite Layered Soil Model Considering Outlier Dispersion

Xiao,

Cai,

et al. 2023

IEEE Access

View full text Add to dashboard Cite

Accurate soil structure models are crucial references for substation grounding system design. Typically, inversion algorithms are employed to obtain uniform or horizontal layered soil models based on measured apparent resistivity. However, soil resistivity outlier distribution areas can affect the accuracy of these inversion algorithms, particularly when these areas are near the surface. Traditional algorithms do not account for the outlier distribution of soil resistivity, leading to significant discrepancies between the calculated results of the design scheme and actual operation, thereby impacting the safety and economy of the grounding system. Therefore, this paper proposes an inversion method for soil structures with outlier distribution characteristics based on deep belief networks (DBNs). Firstly, we introduce a statistical criterion for identifying the outlier distribution characteristics of soil resistivity. Subsequently, we construct a database of soil models with outlier distribution characteristics to train the DBN. Finally, we verify the inversion accuracy of the optimal DBN using apparent resistivity data measured in a 220 kV substation and the Qinghai-Tibet Railway. The results demonstrate that the inversion accuracy of the method proposed in this paper is comparable to that of the traditional method for horizontally layered soil but exhibits a remarkable improvement of approximately 40% when dealing with soil apparent resistivity exhibiting outlier distribution characteristics. INDEX TERMSGrounding, soil model, outlier dispersion, deep belief network. ABBREVIATION LIST DBN Deep belief networks. CDEGS Current Distribution, Electromagnetic Interference, Grounding, and Soil Structure Analysis Package. GA Genetic algorithm. ANN Artificial neural network. RMSE Root mean square error. ML Machine learning. RBM Restricted Boltzmann Machine. MSE Mean squared error. The associate editor coordinating the review of this manuscript and approving it for publication was Kathiravan Srinivasan . M-MSE Mini-batch training MSE. F-FMSE Full-batch train MSE. V-MSE Validation MSE. SPSS Statistical Package for the Social Sciences. ROC Receiver operating characteristic curve. AUC The area under the ROC curve. SD Steepest descent method. SA Simulated Annealing. BFGS Broyden-Fletcher-Goldfarb-Shanno algorithm. PSO Particle swarm optimization. ρ iThe resistivity of the i th layer of soil. h iThe thickness of the i th layer of soil. S(x 0 ,y 0 ,z 0 ) The coordinates of the center of the outlier dispersion area.

show abstract

Section: Introductionmentioning

confidence: 99%

Optimal Inversion Method for Composite Layered Soil Model Considering Outlier Dispersion

Xiao,

Cai,

et al. 2023

IEEE Access

View full text Add to dashboard Cite

show abstract

“…Step and touch voltages should also be eliminated according to IEC 60749-1:2007 [17] (pp. [59][60][61][62][63][64][65][66][67][68][69][70]. From the six usual types of electrodes (land-shallow horizontal, land vertical, land-deep well, sea, shore-beach, shore-pond) according to [17] (p. 19), the shoreline pond electrode was selected for which the determination of the electric field and the potential rise was calculated according to the guidelines of CIGRE B4.61 675:2017 [17].…”

Section: Introductionmentioning

confidence: 99%

“…The detailed solution of the field of a shoreline pond anode electrode is mentioned in technical reports about Italy-Greece Interconnection, such as [60]. EPRI proposes the use of numerical algorithms using resistivity data from geophysical methods [45], which are more widely used in grounding electrodes [61] but also in sea electrodes [58,62,63]. In [62], both near and far electric fields were analyzed, using the numerical methods of hemispheroidal, finite volume element and inclined layer, and finally proposes the use of the first two methods [64,65] that have finite limits on the volume of water for the calculation of the scalar potential and ground potential.…”

mentioning

confidence: 99%

Alternative Simplified Analytical Models for the Electric Field, in Shoreline Pond Electrode Preliminary Design, in the Case of HVDC Transmission Systems

et al. 2022

View full text Add to dashboard Cite

In Greece, a new bi-polar high voltage direct current (HVDC) transmission system with a ground return was designed with nominal characteristics of ±500 kV, 1 GW, between Attica in the continental country and the island of Crete, which is an autonomous power system based on thermal diesel units. The interconnection line has a total length of about 380 km. The undersea section is 330 km long. In this paper, the use of the Aegean Sea as an active part of the ground return, based on shoreline pond electrodes, was proposed to avoid EUR 200 Μ of expenses. According to the general guidelines for HVDC electrode design by the International Council on Large Electric Systems (CIGRE) working group B4.61/2017, the electric field and ground potential rise of shoreline electrodes should be studied to analyze safety, electrical interference and corrosion impacts related to the operation of the electrodes. Two kinds of studies are available; one is a simplified approach based on a spherical/pointed electrode centered at the edge of the seashore and seabed, assuming it to be sloping to the horizontal, and the other is a detailed simulated model using a suitable electric field software package. The first approach usually gives more unfavorable results than the second one, especially in the near electric field, while it can not take into account obstacles, i.e., dams, near to electrode position. The second approach demands a detailed description of the wider installation area, which cannot be available during the preliminary study, significant computational time and considerable financial resources for the purchase of a reliable specialized software package. In this research, a two-step modification of the CIGRE simplified model was proposed. The first modification deals with the obstacles in the near electric field, and the second modification deals with the use of a linear current source (instead of a point one), which can give more accurate results. Additionally, the electric field for complex electrode formation is calculated by applying the superposition method, which can be easily achieved using a common software package, i.e., MATLAB. The proposed simplified approaches were applied on shoreline pond electrode locations for the Attica–Crete HVDC interconnection line (between Stachtoroi island in Attica and Korakia beach in Crete), allowing the preliminary study to be conducted swiftly, giving satisfactory results about electric field gradient, ground potential rise and resistance to remote earth of electrodes stations for the near and far electric field.

show abstract

“…W HEN one or more dc transmission lines in a high voltage dc (HVDC) system operate in monopolar mode or bipolar unbalanced mode, large dc currents will flow into the ground through dc grounding electrodes [1], [2], which leads to dc bias of transformers near the grounding electrodes [3]. This problem is frequently reported in practice and poses a great threat to the safe operation of HVDC systems [4].…”

Section: Introductionmentioning

confidence: 99%

A System-Level Suppression Method for DC Bias Based on Reverse Unbalanced Currents in the Same Transmission Section

Lin

et al. 2021

IEEE Access

View full text Add to dashboard Cite

Conventional dc bias suppression strategies mainly rely on a single type of device, such as blocking capacitor or blocking resistance. However, these methods are passive palliatives and cannot restrain dc bias currents from the sources. In the light of this, a system-level suppression method for dc bias is proposed in this paper. The average value of currents flowing through the earth is offset by actively generating unbalanced current through other dc projects in the same transmission section, which will reduce the currents flowing into the neutral transformers and alleviate the negative impacts of dc bias. First, the feasibility of the same section dc continuous power support is analyzed. Then the dc bias suppression strategy based on reverse unbalanced currents is elaborated. By scanning all the theoretical operable solutions of unbalanced current generation modes and the possible switching combinations of blocking capacitors, the optimal dc bias suppression solution is output considering the number of adjusted dc projects, the overload margin of dc projects and neutral dc currents of transformers. The effectiveness and superiority of the proposed method are verified by comparative case studies of the East China power grid. INDEX TERMS DcBias; System-level Suppression Method; Reverse unbalanced currents.

show abstract

Research on Distribution Characteristics of DC Potential Near the UHVDC Grounding Electrode

Cited by 10 publications

References 12 publications

Optimal Inversion Method for Composite Layered Soil Model Considering Outlier Dispersion

Optimal Inversion Method for Composite Layered Soil Model Considering Outlier Dispersion

Alternative Simplified Analytical Models for the Electric Field, in Shoreline Pond Electrode Preliminary Design, in the Case of HVDC Transmission Systems

A System-Level Suppression Method for DC Bias Based on Reverse Unbalanced Currents in the Same Transmission Section

Contact Info

Product

Resources

About