Energies

Research

17 pages, 3384 KiB

Open AccessArticle

Improved Testing Method Using the Multi-Transformers Synthetic Circuit to Verify Capacitive Charging Current Switching Capability of High-Voltage Circuit Breakers

by Yun-Seong Kim, Jong-Hyuk Choi, Rahul S. Patil and Min-Won Park

Energies 2023, 16(12), 4764; https://doi.org/10.3390/en16124764 - 16 Jun 2023

Viewed by 1054

Abstract

To perform a capacitive current switching test (CCT) at AC extra-high-voltage (EHV) and above level, this paper proposes a new multi-transformer synthetic circuit (MTSC) test method that replaces the general synthetic test method using capacitor banks. An MTSC method has a simpler circuit [...] Read more.

To perform a capacitive current switching test (CCT) at AC extra-high-voltage (EHV) and above level, this paper proposes a new multi-transformer synthetic circuit (MTSC) test method that replaces the general synthetic test method using capacitor banks. An MTSC method has a simpler circuit structure compared to other synthetic testing methods and has higher equivalence (especially recovery voltage and TRV) and validity. Using this method, CCTs for circuit breakers (CBs) of the AC 420 kV voltage class were performed as a field test using the IEC 62271-100 standard. To verify that the test method was valid, test results were analyzed and compared with the requirements of a standard. Consequently, the MTSC method completely covered the requirements of the standard. Full article

(This article belongs to the Special Issue Advances in High Voltage Engineering)

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13 pages, 5070 KiB

Open AccessArticle

Electrical Phenomena on Fully Airborne Vertical Electric Antennas in Extreme Weather Conditions

by Tomasz Aleksander Miś and Józef Modelski

Energies 2023, 16(1), 52; https://doi.org/10.3390/en16010052 - 21 Dec 2022

Cited by 1 | Viewed by 862

Abstract

This is a conference extension of the paper ‘Investigation on the mature storm cloud’s electric field using long airborne antennas’. The use of vertical antennas (including the VEDs—Vertical Electric Dipoles), lifted up by aerostats to high altitudes without being anchored to the ground, [...] Read more.

This is a conference extension of the paper ‘Investigation on the mature storm cloud’s electric field using long airborne antennas’. The use of vertical antennas (including the VEDs—Vertical Electric Dipoles), lifted up by aerostats to high altitudes without being anchored to the ground, presents numerous advantages in comparison with large terrestrial VLF (Very Low Frequency) antenna structures. A slow-moving floating-earth conductor—a vertical wire antenna—is subjected to intense electrification mechanisms in the atmosphere and inside the cloud layers, producing additional risks for the transmitter and the flight train itself. The electrical potential achieved in this process is, therefore, compared with the flashover voltages over the antenna’s upper fixing point, defining the voltage margins at which the VLF transmitter is able to operate. The electrification processes are also compared to the model based on experimental data on the occurrence of corona discharges over a long, vertical wire traversing a storm cloud layer. The external electric field strength (around the antenna wire) is calculated and compared with older experimental data for storm clouds for various locations, showing the correctness of the proposed analytical electrification model, and, therefore, expanding it with the loss of the electric charge via corona. Full article

(This article belongs to the Special Issue Advances in High Voltage Engineering)

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11 pages, 3440 KiB

Open AccessArticle

Development of Future Compact and Eco-Friendly HVDC Gas Insulated Systems: Test Verification of Shape-Optimized DC Spacer Models

by Haoluan Li, Nabila Zebouchi, Manu Haddad, Alistair Reid and Egbert Ekkel

Energies 2022, 15(22), 8563; https://doi.org/10.3390/en15228563 - 16 Nov 2022

Viewed by 1172

Abstract

Spacers for the HVDC GIS/GIL play an important role in mechanically supporting conductors and separating compartments. At the same time, their insulation performance affects the stability and safety of system operation. Design rules and knowledge specific to AC spacers do not apply to [...] Read more.

Spacers for the HVDC GIS/GIL play an important role in mechanically supporting conductors and separating compartments. At the same time, their insulation performance affects the stability and safety of system operation. Design rules and knowledge specific to AC spacers do not apply to those of DC spacers. Considering the shape influence on the surface electric field intensity of the spacer under HVDC applied voltage, as determined in our previous work, an optimized shape of a spacer model based on finite element electric field calculations and using standard HVAC alumina filled epoxy material and two novel types of materials were studied. The simulation’s results show that the DC shape optimization of the spacers can effectively reduce the electric field magnitudes along the spacer under different temperature gradients. To verify practically these findings, this paper presents the reduced scale gas insulated prototype that was constructed, the optimized DC spacers that were fabricated and the DC testing results using SF₆-free surrounding gas: C4-Perfluoronitrile (C4-PFN, 3M^TM Novec^TM 4710)/CO₂ and Trifluoroiodomethane (CF₃I)/CO₂. The results show that the shape-optimized spacer models made of conventional HVAC filled epoxy material have successfully passed the tests up to the maximum applicable ±123 kV DC exceeding thus ±119 kV DC that corresponds to the nominal voltage ±500 kV DC of the full scale. Full article

(This article belongs to the Special Issue Advances in High Voltage Engineering)

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15 pages, 3881 KiB

Open AccessArticle

Research on the Application of Uncertainty Quantification (UQ) Method in High-Voltage (HV) Cable Fault Location

by Bin Yang, Zhanran Xia, Xinyun Gao, Jing Tu, Hao Zhou, Jun Wu and Mingzhen Li

Energies 2022, 15(22), 8447; https://doi.org/10.3390/en15228447 - 11 Nov 2022

Cited by 1 | Viewed by 1117

Abstract

In HV cable fault location technology, line parameter uncertainty has an impact on the location criterion and affects the fault location result. Therefore, it is of great significance to study the uncertainty quantification of line parameters. In this paper, an impedance-based fault location [...] Read more.

In HV cable fault location technology, line parameter uncertainty has an impact on the location criterion and affects the fault location result. Therefore, it is of great significance to study the uncertainty quantification of line parameters. In this paper, an impedance-based fault location criterion was used for an uncertainty study. Three kinds of uncertainty factors, namely the sheath resistivity per unit length, the equivalent grounding resistance on both sides, and the length of the cable section, were taken as random input variables without interaction. They were subject to random uniform distribution within a 50% amplitude variation. The relevant statistical information, such as the mean value, standard deviation and probability distribution, of the normal operation and fault state were calculated using the Monte Carlo simulation (MCS) method, the polynomial chaos expansion (PCE) method, and the univariate dimension reduction method (UDRM), respectively. Thus, the influence of uncertain factors on fault location was analyzed, and the calculation results of the three uncertainty quantification methods compared. The results indicate that: (1) UQ methods are effective for simulation analysis of fault locations, and UDRM has certain application prospects for HV fault location in practice; (2) the quantification results of the MCS, PCE, and UDRM were very close, while the mean convergence rate was significantly higher for the UDRM; (3) compared with the MCS, PCE, and UDRM, the PCE and UDRM had higher accuracy, and MCS and UDRM required less running time. Full article

(This article belongs to the Special Issue Advances in High Voltage Engineering)

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11 pages, 4274 KiB

Open AccessArticle

Effects of Hot Pressing Temperature and Pressure on Dielectric Properties of Aramid Insulating Paper

by Yuanxin Yao, Meng Huang, Jie Ma, Yanxiao Su, Sheng Shi and Chunhe Wang

Energies 2022, 15(21), 8314; https://doi.org/10.3390/en15218314 - 7 Nov 2022

Cited by 5 | Viewed by 1533

Abstract

The hot pressing parameters and fiber ratio have an important influence on the dielectric properties of aramid insulating paper. In order to deeply explore its influence and the mechanism behind it, aramid insulating papers were made with different hot pressing temperatures and pressures [...] Read more.

The hot pressing parameters and fiber ratio have an important influence on the dielectric properties of aramid insulating paper. In order to deeply explore its influence and the mechanism behind it, aramid insulating papers were made with different hot pressing temperatures and pressures as well as fiber ratios. Its tightness, dielectric constant, and AC breakdown strength were tested, and its microstructure was analyzed by scanning electron microscopy. It was found that with an increase in hot pressing temperature, pressure, and fibrid content, the overall dielectric constant of the insulating paper showed a slight upward trend, while the tightness and AC breakdown strength continued to increase. Hot pressing temperature and pressure have a synergistic effect on the dielectric properties of insulating paper. The effects of these two parameters on the dielectric properties of insulating paper are similar, while the AC breakdown strength is greatly affected by the fiber ratio. In this paper, the influence mechanism by which the microstructure and fiber crystallinity of insulating paper is affected in the hot pressing process is discussed. Full article

(This article belongs to the Special Issue Advances in High Voltage Engineering)

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16 pages, 2440 KiB

Open AccessArticle

A Numerical Study on the Decomposition and Diffusion Characteristics of SF₆ in Gas-Insulated Switchgear with Consideration of the Temperature Rising Effect

by Chenglong Jia, Wenbin Zhao, Yong Zhu, Wu Lu and Zhong Tang

Energies 2022, 15(21), 7834; https://doi.org/10.3390/en15217834 - 22 Oct 2022

Cited by 1 | Viewed by 1202

Abstract

The optimized concentration of SF₆ gas is the key to maintaining a good insulation performance by GIS equipment. The precise measurements of the SF₆ concentration and decomposition byproducts could be used to indicate the remaining GIS insulation level during long-term operations. [...] Read more.

The optimized concentration of SF₆ gas is the key to maintaining a good insulation performance by GIS equipment. The precise measurements of the SF₆ concentration and decomposition byproducts could be used to indicate the remaining GIS insulation level during long-term operations. In this paper, a finite-element simulation model was created to investigate the SF₆ gas decomposition and diffusion dynamics. A theoretical analysis and simulation of the overheating fault, i.e., the contact between the GIS disconnect switches, were carried out, followed by an estimation of the SF₆ decomposition and diffusion characteristics caused by the local heating faults, based on the calculated flow velocity field and temperature field. Full article

(This article belongs to the Special Issue Advances in High Voltage Engineering)

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20 pages, 14305 KiB

Open AccessArticle

Model Investigations on Electric Discharges over Balloon-Borne Stratospheric VLF Antennas

by Tomasz Aleksander Miś, Józef Modelski and Maciej Ciuba

Energies 2022, 15(18), 6805; https://doi.org/10.3390/en15186805 - 17 Sep 2022

Cited by 2 | Viewed by 1359

Abstract

Long linear antennas for very low frequency radio transmissions, supported by aerostats, unanchored, and raised to high altitudes, present themselves as slow-moving, highly conductive disturbances in cloud layers, acquiring an electrical charge and being subjected to intense coronae. High electric field strength values [...] Read more.

Long linear antennas for very low frequency radio transmissions, supported by aerostats, unanchored, and raised to high altitudes, present themselves as slow-moving, highly conductive disturbances in cloud layers, acquiring an electrical charge and being subjected to intense coronae. High electric field strength values around those objects increase the risk of lightning strikes, which could be disastrous to the mechanical structures of the balloon mission (both the antenna and the balloon) and the radio transmitter. This paper aims to investigate the inception of lightning strikes over two essential elements of such missions: a talc-covered latex (balloon material) and the model of the linear antenna, made of different materials. Based on the high-voltage experiments with the recorded electrical discharges, the properties, functions, and possible ameliorations of the talc cover are presented, as well as the basic characteristics of lightning forms around the very long antenna system, with a proposition of design requirements and constraints reflecting the safety of the balloon missions employing a VLF antenna from lightning strikes. Full article

(This article belongs to the Special Issue Advances in High Voltage Engineering)

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12 pages, 3109 KiB

Open AccessArticle

Design of an Anti-Corona Device for HVAC Substation Connectors

by Ane Miren Larrea, Manuel De La Hoz, Agurtzane Etxegarai, Angel Javier Mazon and Itxaso Aranzabal

Energies 2022, 15(16), 5781; https://doi.org/10.3390/en15165781 - 9 Aug 2022

Viewed by 1544

Abstract

One of the aspects to consider during high-voltage (HV) equipment design is the reduction in the probability of corona effect onset. Indeed, the corona effect is related to high electric field values beyond the equipment’s insulation levels and insulation strength, among other factors. [...] Read more.

One of the aspects to consider during high-voltage (HV) equipment design is the reduction in the probability of corona effect onset. Indeed, the corona effect is related to high electric field values beyond the equipment’s insulation levels and insulation strength, among other factors. This issue can be addressed during the design step, either by modifying the geometry of the electrical device or by including additional elements in the equipment structure to smooth out the voltage gradient along critical regions, such as anti-corona devices. The study of anti-corona devices for HV insulators is well documented, in contrast to substation connectors. Therefore, the present study proposed the design of a novel anti-corona device for HV substation connectors, including a method for the selection of its dimensions. This study shows that the relationship between the dimensional design variables and the critical electrical field on the connector is described by linear and rational functions. Thus, the design process times are cut down due to a reduction in the number of simulations required to run the assessment of the anti-corona device arrangement impact. Full article

(This article belongs to the Special Issue Advances in High Voltage Engineering)

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