A Study for the Measurement of the Minimum Clearance Distance between the 500 kV DC Transmission Line and Vegetation

High voltage direct current (HVDC) transmission is being widely implemented for long-distance electrical power transmission due to its specific benefits over high voltage alternating current (HVAC) transmission. Most transmission lines pass through forests. Around the HVDC lines, an arc to a nearby tree may be produced. Thus, there should be a minimum possible clearance distance between a live conductor and a nearby tree, named the minimum vegetation clearance distance (MVCD), to avoid short-circuiting. Measurement of minimum clearance distance between the conductor and trees is a significant challenge for a transmission system. In the case of HVAC transmission, a large amount of research has been undertaken in the form of the Gallet equation for the measurement of this distance, whereas for HVDC transmission no substantial work has been done. An equivalent AC voltage value can be derived from the DC voltage value in order to use the Gallet equation. This paper presents an experimental measurement technique for determining the MVCD at 500 kV to verify the results obtained from the Gallet equation in the case of DC voltage. Performing the experiment with a 500 kV DC line is not possible in the laboratory due to safety concerns. Therefore, an experiment up to 60 kV is conducted to measure the MVCD for DC voltage. The measured results achieved from the experiment are then extrapolated to calculate the MVCD at 500 kV.

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A Novel Pilot Protection Principle Based on Modulus Traveling-Wave Currents for Voltage-Sourced Converter Based High Voltage Direct Current (VSC-HVDC) Transmission Lines

Energies ◽

10.3390/en11092395 ◽

2018 ◽

Vol 11 (9) ◽

pp. 2395 ◽

Cited By ~ 4

Author(s):

Xiangyu Pei ◽

Guangfu Tang ◽

Shengmei Zhang

Keyword(s):

High Voltage ◽

Direct Current ◽

Transmission Lines ◽

Traveling Wave ◽

Hvdc Transmission ◽

High Voltage Direct Current ◽

Hvdc Transmission Lines ◽

Dc Line ◽

Voltage Sourced Converter ◽

Pilot Protection

Protection for transmission lines is one of crucial problems that urgently to be solved in constructing the future high-voltage and large-capacity voltage-sourced converter based high voltage direct current (VSC-HVDC) systems. In order to prevent the DC line fault from deteriorating further due to the failure of main protection, a novel pilot protection principle for VSC-HVDC transmission lines is proposed in this paper. The proposed protection principle is based on characteristics of modulus traveling-wave (TW) currents. Firstly, the protection starting-up criterion is constructed by using the absolute value of the 1-mode TW current gradient. Secondly, the fault section identification is realized by comparing the polarities of wavelet transform modulus maxima (WTMM) of 1-mode initial TW currents acquired from both terminals of the DC line. Then, the selection of fault line is actualized according to the polarity of WTMM of local 0-mode initial reverse TW current. A four-terminal VSC-based DC grid electromagnetic transient model based on the actual engineering parameters is built to assess the performance of the proposed pilot protection principle. Simulation results for different cases prove that the proposed pilot protection principle is excellent in reliability, selectivity, and robustness. Moreover, the data synchronization is not required seriously. Therefore, the proposed novel pilot protection principle can be used as a relatively perfect backup protection for VSC-HVDC transmission lines.

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Stability Improvement of The Iraqi Super Grid (400kV) using High Voltage Direct Current (HVDC) Transmission

Journal of Engineering ◽

10.31026/j.eng.2021.11.05 ◽

2021 ◽

Vol 27 (11) ◽

pp. 64-74

Author(s):

Zainab Nadhim Abbas ◽

Firas Mohammed Tuaimah

Keyword(s):

High Voltage ◽

Direct Current ◽

Transmission Lines ◽

Short Circuit ◽

Alternating Current ◽

National Network ◽

Hvdc Transmission ◽

High Voltage Direct Current ◽

Dc Line ◽

Bipolar Type

This research analyzes the level of the short circuit effect of the Iraqi super network and decides the suitable location for the High Voltage Direct Current (HVDC) connections in order to obtain the best short circuit reduction of the total currents of the buses in the network. The proposed method depends on choosing the transmission lines for Alternating current (AC) system that suffers from high Short Circuit Levels (SCLs) in order to reduce its impact on the transmission system and on the lines adjacent to it and this after replacing the alternating current (AC) line by direct current (DC) line. In this paper, Power System Simulator for Engineering (PSS/E) is used to model two types of HVDC lines in an effective region of Iraqi networks and to perform comparative studies to test the location of Short Circuit Levels (SCLs) between an actual AC and AC/DC case study in a portion of the Iraqi national network. The results proved the effectiveness of this method in eliminating severe faults and unwanted short currents, and the results showed that the bipolar type is better in reducing Short Circuit Levels of the Iraqi network.

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Global experience of HVDC composite insulators in outdoor and indoor environment

REVIEWS ON ADVANCED MATERIALS SCIENCE ◽

10.1515/rams-2020-0050 ◽

2020 ◽

Vol 59 (1) ◽

pp. 606-618

Author(s):

Mohammad Akbar ◽

Basharat Mehmood

Keyword(s):

High Voltage ◽

Direct Current ◽

Transmission Lines ◽

Power Transmission ◽

Green Energy ◽

Attractive Alternative ◽

Hvdc Transmission ◽

Ceramic Insulators ◽

High Power Transmission ◽

Aging Performance

AbstractHigh-voltage direct current (HVDC) transmission is known as green-energy transfer technology and has recently become an attractive alternative of high-voltage alternating current (HVAC) due to its high-power transmission capability and lower power loss. Use of composite insulators on direct current (DC) transmission lines experienced rapid growth in recent years due to their high hydrophobicity and better performance in contaminated environment than conventional ceramic insulators. During their service operation on DC lines, insulators are prone to more accumulation of contaminants due to unidirectional electric field. The contaminants under wet conditions allow leakage current to flow on the insulator surface. Being organic in nature, polymeric insulators have a tendency to age under the combined effects of electrical and environmental stresses. To fully understand the long-term aging performance of DC composite insulators, a detailed survey was considered necessary. Towards that end, this paper critically summarizes worldwide experience of aging performance of composite insulators in the field as well as in laboratory conditions.

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Feasibility Evaluation on Elimination of DC Filters for Line-Commutated Converter-Based High-Voltage Direct Current Projects in New Situations

Energies ◽

10.3390/en14185770 ◽

2021 ◽

Vol 14 (18) ◽

pp. 5770

Author(s):

Xiaodong Li ◽

Zheng Xu

Keyword(s):

High Voltage ◽

Direct Current ◽

Power Transmission ◽

Rapid Development ◽

Maintenance Cost ◽

Attractive Alternative ◽

Stable Operation ◽

Long Distance ◽

High Voltage Direct Current ◽

Feasibility Evaluation

The line-commutated converter (LCC)-based high voltage direct current (HVDC) technology has been widely applied on long-distance and bulk-capacity power transmission occasions. Due to the terrible interferences in the vicinity of communication lines, DC filters (DCFs) are always installed to mitigate the interferences within acceptable levels for almost all in-service overhead line transmission LCC-HVDC schemes. With the rapid development of the communication technology, however, the anti-interference capability of the telephone system has been remarkably improved. Thus, the original purpose of employing DCFs has been virtually absent, and the necessity of the DCFs shall be re-evaluated in sufficient depth not only for new LCC-HVDC projects, but also in the case of refurbishment of older projects. To demonstrate this constructive topic, this paper carries out a commercial ±800 kV/8000 MW LCC-HVDC project as an illustrative example to analyze and discuss those crucial aspects, which may influence the LCC-HVDC stable operation and reliability after removing the DCFs. Then, the paper studies the harmonic voltage/current stresses of the DC equipment, the DC loop low-order harmonic resonances, and the overvoltage under the switching surge and lightning stroke. Finally, it is concluded that the DCF elimination mainly affects the harmonic steady-state stresses of the DC equipment, but has little influence on the transient stresses. For the refurbishment of older projects, the evaluation on the cost between the DCFs’ maintenance cost and the equipment modification is needed for the DCFs’ elimination. For new LCC-HVDC projects, the DCFs’ elimination or at least simplification may be a more economical and attractive alternative, thereby reducing the footprint and cost.

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Corona Loss Minimization on High Voltage Transmission Line Network using Bundled Conductors.

International Journal of Engineering and Advanced Technology - Regular Issue ◽

10.35940/ijeat.c5363.029320 ◽

2020 ◽

Vol 9 (3) ◽

pp. 887-891

Keyword(s):

Transmission Line ◽

Transmission Lines ◽

Power Transmission ◽

Hessian Matrix ◽

Electrical Power ◽

Power Transmission Lines ◽

Long Distance ◽

Power Stations ◽

Line Network ◽

Corona Losses

Electrical power generated and transmitted at a long distance away from the power stations is usually affected by inherent transmission line losses. The Ohmic and Corona losses which are predominantly common in power transmission lines are considered in this paper. These two losses are mathematically modeled with and without embedded bundled conductors. The resultant model which is a non-linear multivariable unconstrained optimized equation is minimized using the Hessian matrix determinant method for stability test purposes. The results obtained show that corona losses are minimized with embedded bundled conductors at a very low current value with large spacing distance between the bundled conductors. The decrease in the corona loss which is a consequence of spacing adjustment of the 2, 3, and 4 strands of bundled conductors was plotted using MATLAB 7.14. The plots obtained are in conformity with the inverse relation between corona loss and conductor spacing.

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Improving the Performance of Power Transmission via Ultra High Voltage Direct Current (UHVDC)

MATEC Web of Conferences ◽

10.1051/matecconf/201817302028 ◽

2018 ◽

Vol 173 ◽

pp. 02028

Author(s):

Yongbei Li

Keyword(s):

High Voltage ◽

Direct Current ◽

Power Transmission ◽

Network System ◽

Power Network ◽

Long Distance ◽

High Voltage Direct Current ◽

Interactive Network ◽

Increasing Demand ◽

Ultra High Voltage

To meet people’s increasing demand for power, the power network system is developing. And the concept, essence and an energy interactive network plan of “Smart Grid” is proposed. However, some technical issues concerned in power network system appear. It is the key to improve the efficiency of transmission in the grid network. And the feasibility of applying Ultra High Voltage Direct Current (UHVDC) transmission to improve efficiency reliably is adequately expounded and proved. There are many countries using this method, especially China. Direct Current (DC) transmission is an important technology for high voltage, large capacity, and long distance transmission. Development and characteristics of UHVDC transmission and its development prospects in China are also introduced in this paper.

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Liquefied natural gas (LNG) and DC electric power transfer system by cryogenic pipe of superconducting DC power transmission (SCDC)

Journal of Physics Conference Series ◽

10.1088/1742-6596/2088/1/012019 ◽

2021 ◽

Vol 2088 (1) ◽

pp. 012019

Author(s):

Sataro Yamaguchi ◽

Yury Ivanov ◽

Linda Sugiyama

Keyword(s):

Natural Gas ◽

Transmission Lines ◽

Power Transmission ◽

Electrical Power ◽

Liquefied Natural Gas ◽

Gas Pipeline ◽

Long Distance ◽

Hybrid Energy ◽

Transport Distance ◽

Transmission Pipeline

Abstract We propose a hybrid energy transmission pipeline that combines the liquefied natural gas (LNG) cryogenic pipelines and superconducting direct current (DC) electrical power transmission cable system (SCDC). The system design is based on experimental data from the SCDC Ishikari project in Japan and related laboratory experiments. The particular structure of the hybrid cryogenic pipe connects the thermal radiation shield of the pipe that contains the DC high temperature superconducting (HTS) electrical cable to the LNG pipe and significantly reduces the heat leak into the SCDC pipe. Because the specific heat of LNG is higher than that of liquid nitrogen and the LNG transfer rate is quite high, the thermal loss of the SCDC cable becomes only 1/100 that of present-day conventional copper cables, far below the factor 1/10 reduction achievable by a stand-alone SCDC transmission lines. The LNG temperature rises by less than 2 K over a 100 km transport distance, which is negligible in actual use. LNG also saves significantly on pumping power compared to a natural gas pipeline. To liquefy the LNG at cryogenic temperature from natural gas at ambient temperature requires a large refrigerator that consumes enormous power. The gas pipeline, however, needs a compressor to produce high-pressure gas, which also consumes a massive amount of power. Due to these considerations, the proposed hybrid system is a viable design for the long-distance joint transportation of LNG and electricity.

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