The working current of DC grounding electrodes is constantly increasing with the rapid development of high-voltage direct current systems. Thus, the temperature rise of grounding electrode conductors is increasingly becoming an important safety factor. Therefore this study measured the soil temperature characteristics of water content and resistivity; established an electric heat coupling finite element model for DC grounding electrodes that is based on current field and temperature field theories to analyse the temperature changes in common DC grounding electrodes. In contrast to traditional models, the proposed model realises electric heat coupling field calculation by considering the mutual influence of temperature rise and soil parameters. The results show that the soil resistivity increases with increasing temperature and the soil resistivity change further influence the temperature changes of the grounding electrodes. The change in grounding electrode temperature rise is not steady and includes a sharp growth stage.

https://ietresearch.onlinelibrary.wiley.com/doi/pdf/10.1049/iet-smt.2014.0157

Influence of soil temperature characteristic on the grounding electrode temperature rise

This paper focus on the Modeling and Calculation of DC current distribution in AC power grid induced under HVDC Ground-Return-Mode. Applying complex image method and boundary element method, a new field-circuit coupling model was set up. Based on the calculation result with complex image method, this paper derived the modification factor for induced earth potential from practical measurement, which increased the accuracy of calculation. The modification method is helpful for evaluation on the effect of means used for blocking the dc-bias current in transformer neutral and also useful for the forecast of the DC current distribution when the power grid is in different line connection mode. The DC distribution character in Guangdong power grid is shown and suggestion is proposed that the mitigation of dc-bias should start from those substations whose earth-potential is highest.

/pdf/simulation-on-dc-current-distribution-in-ac-power-grid-under-ra2sq6c2j5.pdf

Simulation on DC Current Distribution in AC Power Grid under HVDC Ground-Return-Mode

DC transmission system in monopole-grounded return operation mode may lead to DC magnetic bias of some transformers in AC power system. In order to develop the management measures of DC bias effectively, it is necessary to study the distribution of DC magnetic bias current in AC power system. Based on the direct field-circuit coupled method, considering the effect of multi-layer soil model on the electrical current field and the impact of the transmission lines on the earth surface potential (ESP) distribution, the DC magnetic bias calculation models of ±800kV Xi-Zhe and ±800kV Ling-Shao UHV transmission project were built. The modeling range and the ground grid parameters were determined, while the soil model is modified as well. The calculated values of DC biasing current were compared with the test result and the total average error of each testing station is no more than 5%, which verifies the accuracy of the calculation model. This research can provide reference to the calculation of DC current distribution in large AC power system and the management of DC magnetic bias.

Study of DC-bias current distribution in AC power system based on direct field-circuit coupled model

When earth is used as the current return path of ultra high-voltage direct current (UHVDC) system, great DC current will flow in the earth, which will bring about great ground potential differences in a large area around the DC grounding electrodes. To investigate UHVDC grounding current, A three-layer earth model combining vertical and horizontal layers is established by analyzing the ground soil structure. Based on quasi-newton method, the parameters of soil structure obtained from unequally spaced Wenner four-probe test data are optimally estimated. According to the model, the current and voltage of ground have been calculated around the UHVDC electrode site and used to analyze the leakage situation of grounding current in soil structure of Sichuan Xiluodu Hydropower Station . The decline of current in super stratum is different because of distance. The choice of UHVDC electrode site is extremely sensitive to terrain and geological condition, and that Xiluodu and Xiangjiaba Hydropower Station are located between Sichuan and Yunnan border area of high altitude, heavily covered ice and large mountainous districts. Finally, some suggestions about the choice of UHVDC electrode site were provided in this paper.

Calculation of DC grounding current distribution by UHVDC mono-polar operation with ground return

This paper studies the exciting current of transformer affected by DC bias in the Tibet soil structure when the UHVDC system is working in monopole state. Firstly, the model calculating the ground potential for a typical frozen soil of the Tuotuo River substation was described, and then the ground potential around the UHVDC grounding electrode for five-layer soil in summer and winter was calculated. According to the soil parameters, the magnetic bias current of the transformer were calculated. Results indicate that the distance is less than about 4 km and the earth potential is variable in different season. The substation electrode design parameters are complex, so building substation is very inconvenient. And when the distance is adjusted from 4 km to 8km, the earth potential is changed from 400 V to 200 V, the exciting current decreased from 45mA to 5mA, the waveform unbalance will also decrease.

Soil structure effect on transformer DC bias

The HVDC transmission system maybe operated in ground return status when the system is in debug or failure. If the ground return current of the HVDC system is large enough, some transformers in AC system may be under DC bias. In this paper, a numerical method is presented to calculate the DC current distribution in AC power system caused by a HVDC system. The method of moments is used to calculate the electric fields in complex earth structure caused by all the grounding systems including the DC grounding electrodes, the AC substation grounding systems, and the long metal pipe lines. The circuit equations are coupled to the moment method to combine the AC transmission lines with the grounding systems. Current distribution of the power system above 220 kV around Chuncheng substation in Guangdong province is analyzed when the Gui-Guang HVDC system is in ground return status. The results are compared with those of testing on site.

Estimation of DC Current Distribution in AC Power System Caused by HVDC Transmission System in Ground Return Status

Handle everyday research tasks with reliable, citation-backed results

Your personal Research Agent to handle research tasks with citation-backed results

Popular Tasks used by Researchers

How can I help with your research?

Meet SciSpace

Get more enhanced response by uploading the PDFs you want me to reference.

No relevant PDFs in your library

SciSpace is the AI research assistant for academics. Run systematic literature reviews on 280M+ papers, and write papers with cited sources. Trusted by 1M+ students, PhDs & researchers.

SciSpace | AI for Research

Analyze PDFs

Code & Manuscripts

Funding & Grants

Literature & Patents

Medical & Clinical Data

Systematic Review

Visualize & Present

Web & Data

Build a Google Scholar-like website for your research.

Build a website

Create charts and images for your research

Create a Chart

Write a paper for submission to a journal

Draft a manuscript

Patent Search

Design eye-catching scientific posters in minutes.

Scientific Poster Generation

Systematic Literature Review

One task is running at the moment. Your messages will be shown right after.

Drag and drop or click here to browse

Loved by <highlight>1 million+</highlight> researchers

Extract a list of specific topics and their sources from unstructured text

Topics

Compare and analyze relevant papers that matches with your search

Papers

Get insights from PDFs and bookmarked papers from your library

My library

Recent searches

Try searching for:

Catch AI-generated content in scholarly and non-scholarly content

{ai} Detector

Ai Writer

Get PDF Summaries, highlighted text explanations 

Chat with PDF

Effortlessly create in-text citations and bibliographies in APA and 2,500 other formats

Citation generator

Get explanations, summaries, and answers on academic papers

Ease up your research workflow with {scispace}'s cohort of exciting AI tools

Elevate your academic writing skills and convey your ideas the way you want

Paraphraser

Explore our range of reading and writing tools

Your file is being prepared and should be ready in a few minutes. If it's a large file, it might take a bit longer. You can close this window, and we'll email you the file when it's done.

You have reached a maximum limit of <strong>{limit}</strong> columns in the table. Remove at least <strong>1</strong> column to add or create another one.

Cui Xiang

Author Tools

Chat about Author

Papers

Estimation of DC Current Distribution in AC Power System Caused by HVDC Transmission System in Ground Return Status