Gas Insulated Substation Research Articles

Density-functional theory study of SnSe/GeSe heterostructure for gaseous sulfur hexafluoride decomposition products sensing

Partial discharge, local overheating and other factors will lead to the decomposition of superior dielectric gas sulfur hexafluoride (SF6) used in gas insulated substations (GIS). Detecting gaseous sulfur hexafluoride (SF6) decomposition products by gas sensors to diagnose early latent insulation failures is a potential approach to guarantee safety and reliability of gas insulated substations (GIS). However, the main difficulties in the detection of SF6 decomposition products lie in sensitivity, operating temperature and sulfur poisoning of the sensor. Metal oxide selenides (MOSs)-based gas sensors suffer from high working temperature, long recovery time, and sulfur poisoning. Two dimensional selenides-based chemiresistor-type gas sensors have been reported to detect certain gases at room temperature. Compared with pristine materials, heterostructures usually have narrower band gaps and higher carrier mobility which promise low power and sensitivity. In this work, a SnSe/GeSe van der Waals heterostructure model is constructed and optimized to investigate the gas sensing properties by density functional theory (DFT) calculations. Compared with the pristine SnSe and the pristine GeSe, the SnSe/GeSe heterostructure exhibits huge adsorption energy and comparatively large charge transfer to the SF6 decomposition gases. The band structure analysis, charge analysis, electron localization function (ELF), and density of states (DOS) analysis suggest that the excellent sensing properties are contributed to the synergistic effect between the SnSe and the GeSe layers: both the layers transfer charge and orbitally interact with gas molecules. Besides, physical adsorption of the SF6 decomposition gases on SnSe/GeSe heterostructure avoids sulfur poisoning of the material, promising the recoverability and repeatability of detection. This study provides theoretical bases for the repeatable detection of SF6 decomposition products by SnSe/GeSe heterostructures and its potential in the design of electronic nose.

Scale Modular Test Platform for the Characterization of PD Measuring Systems Using HFCT Sensors.

Today, online partial discharge (PD) measurements are common practice to assess the condition status of dielectrics in high-voltage (HV) electrical grids. However, when online PD measurements are carried out in electrical facilities, several disadvantages must be considered. Among the most important are high levels of changing electrical noise and interferences, signal phase couplings (cross-talk phenomena), and the simultaneous presence of various defects and difficulties in localizing and identifying them. In the last few decades, various PD-measuring systems have been developed to deal with these inconveniences and try to achieve the adequate supervision of electrical installations. In the state of the art, one of the main problems that electrical companies and technology developers face is the difficulty in characterizing the measuring system's functionalities in laboratory setups or in real-world facilities, where simulated or real defects must be detected. This is mainly due to the complexity and costs that the laboratory setups entail and the fact that the facilities are permanently in service. Furthermore, in the latter scenario, owners cannot assign facilities to carry out the tests, which could cause irreversible damage. Additionally, with the aforementioned installations, a comparison of results over time in various locations is not possible, and noise conditions cannot be controlled to perform the characterizations in a correct way. To deal with the problems indicated, in this article, an affordable scale modular test platform that simulates an HV installation is presented, where real on-site PD measuring conditions are simulated and controlled. In this first development, the HV installation comprises a cable system connected at both ends to a gas-insulated substation (GIS). As the most common acquisition technique in online applications is based on the placement of high-frequency current transformer (HFCT) sensors in the grounding cables of facilities, the test platform is mainly adapted to carry out measurements with this type of sensor. The designed and developed test platform was validated to assess its features and the degree of convergence with a real installation, showing the convenience of its use for the appropriate and standardized characterization of PD-measuring systems.

Traveling Wave-Based Fault Location for Gas Insulated Substations

Traveling Wave-Based Fault Location for Gas Insulated Substations

A directional coupler for partial discharge measurements in gas-insulated substations

This paper introduces a directional coupler for partial discharge (PD) measurements in gas-insulated substations (GIS). The sensor comprises a combination of magnetic and electric couplers, effectively segregating forward and backward pulses to enhance PD charge estimation and defect location. The sensor's design was supported with finite element method simulations and measurements conducted in a transverse electromagnetic test bench. Comparative analyses were performed against independent magnetic and electric couplers. The charge estimation and the directional coupler's directivity were evaluated in both the test bench and a full-scale GIS with different PD defects. Initially, the combined magnetic and the electric couplers exhibited undesired interactions, prompting corrective measures. Subsequent adjustments included changes to the electric coupler material and modifications to the magnetic coupler construction. The resulting high-voltage directional coupler performed better than the separated couplers in a GIS with discontinuities. This partial discharge sensor emerges as a candidate for future SF6-free alternative GIS.

Modeling of power reactors for VFTO simulations: Full-scale design in a real application

The shunt reactors operate under a very specific conditions in Gas Insulated Substations - GIS, especially during very fast electromagnetic transients due to switching and maneuver operations. A meticulous electromagnetic analysis for correct design of such power devices, especially on the insulation coordination between turns, discs, and from winding to ground. This article presents a step-by-step modeling methodology based on the Finite Element Method, which is applied during the conception and manufacturing of a real shunt reactor for GISs. Finally, the time- and frequency-domain simulations are compared with experimental data obtained from laboratory tests.

Providing a combined solution to reduce very fast transient overvoltages in gas insulated substations

The use of gas-insulated substations in high voltage levels of power systems is expanding due to its many advantages, such as the need for less space, resistance to environmental pollution, high reliability, and no need for continuous maintenance. One of the phenomena that threatens the insulation distances inside the closed enclosure in these substations is very fast transient voltages. These overvoltages are dangerous for the equipment inside the substation and connected to it as a result of the switching operation of gas-insulated substations, and if repeated, it can damage the internal insulation of the equipment. Also, these transient overvoltages in special cases such as extremely high voltages may cause serious damage to expensive substation equipment. Therefore, in this article, while examining the existing methods to limit very fast transient overvoltages in different and sensitive points of GIS substations, a new combined method based on the simultaneous use of nanocrystalline rings in the busbar and two XLPE cable paths, The direction of connecting the power transformer to the substation is provided. The results of the simulation on the 230 kV side of the GIS substation of Arak city show that the method proposed in this article has the lowest range of overvoltages compared to other methods. By using the proposed combined method, the range of very fast transient overvoltages in the power transformer terminal of the network under study is reduced by 60 % and this reduction can be seen in other points of the substation as well.

Methods for Partial Discharge Calibration in Gas-Insulated Substations for HVDC Power Grids and Charge Evaluation Uncertainty

Methods for Partial Discharge Calibration in Gas-Insulated Substations for HVDC Power Grids and Charge Evaluation Uncertainty

Analysis of the Very Fast Transient Overvoltage in a Nuclear Plant 500kV GIL-GIS System

The simulation models of the 500kV gas-insulated transmission lines (GIL) and gas-insulated substation (GIS) systems in a realistic nuclear plant are presented in the paper. The Very Fast Transient Overvoltage (VFTO) which is generated during switching operations, is analyzed. Some affecting factors on the level of the VFTO are investigated. These factors are the location of the power source, the entrance capacitance of the potential transformer (PT), and the capacitive voltage transformer (CVT). At last, some suggestions on overvoltage calculations or calculations of electromagnetic interference sources are proposed. The conclusions can be used in insulation designing and analyzing the electromagnetic interference on the secondary system in nuclear plants and substations.

Physical mechanism of electrode coatings to suppress wire particle’s firefly motion under DC stress and selecting criterion for in situ applications

The Wire metal particles in gas-insulated equipment such as GIS (Gas-Insulated Substation) and GIL (Gas-Insulated transmission lines) under DC stress present a special firefly motion behaviour, namely a long-term levitation on the surface of conductors. However, the electrode coating, as a key device available to suppress the movement of particles, lacks of a theoretical basis as well as an effective selecting criterion to suppress wire particle’s firefly. In this paper, a test platform is established to obtain the charge dynamics and ionic wind characteristics of the wire particles on the coated electrodes. Experimental results illustrate that, the polarity alternation of wire particle charge due to the space charge accumulation near the wire particles as well as the ionic wind generated by the wire particles, is the key impact factor upon firefly motion. The coated electrodes will reduce the surface conduction current and thereby suppress the particle corona discharge, consequently suppressing the firefly motion by limiting the charge acquisition and ionic wind speed of the wire particles. Based on the above research, a selecting criterion of electrode coating material is further proposed. Electrode coatings is primarily expected to increase the corona onset voltage of the wire particles on the coating surface, so as to lower the ionic wind at the end of the particles less than 1 m s−1. Regarding the high voltage conductor, the coating material with relatively large conductivity is recommended, while for the grounded enclosure, the coating material with smaller conductivity is preferable as to constrain the particles adhere to the enclosure, thereby preventing the firefly motion of wire particle. Both the clarified physical mechanism and the proposed selecting criterion of electrode coating presents theoretical and quantitative guidance for DC GIL design from a specific point of view in suppressing the firefly motion.

Uncovering Gas Insulated Substation Transient Behaviours Using the Equivalent Cable Model

An improved circuit theory approach is proposed for verification of data obtained with the Electro-Magnetic Field (EMF) theory for the study of Gas Insulated Substations (GIS) transient behaviours. The improved circuit theory utilises the concept of an equivalent cable model. The proposed equivalent cable model reduces time and eliminates costs associated with experimentation, which in some cases is not feasible. Also reported is the degree of accuracy in using the proposed model as a benchmark for verification purposes.

Substation technology selection for environment efficient power distribution system in India: an integrated AHP-TOPSIS-based approach

PurposeThis study aims to provide a scientific framework for the selection of suitable substation technology in an electrical power distribution network.Design/methodology/approachThe present paper focuses on adopting an integrated multi-criteria decision-making approach using the Delphi method, analytic hierarchy process (AHP) and technique for order preference by similarity to ideal solution (TOPSIS). The AHP is used to ascertain the criteria weights, and the TOPSIS is used for choosing the most fitting technology among choices of air-insulated substation, gas-insulated substation (GIS) and hybrid substation, to guarantee educated and supported choice.FindingsThe results reveal that the GIS is the most preferred technology by area experts, considering all the criteria and their relative preferences.Practical implicationsThe current research has implications for public and private organizations responsible for the management of electricity in India, particularly the distribution system as the choice of substations is an essential component that has a strong impact on the smooth functioning and performance of the energy distribution in the country. The implementation of the chosen technology not only reduces economic losses but also contributes to the reduction of power outages, minimization of energy losses and improvement of the reliability, security, stability and quality of supply of the electrical networks.Social implicationsThe study explores the impact of substation technology installation in terms of its economic and environmental challenges. It emphasizes the need for proper installation checks to avoid long-term environmental hazards. Further, it reports that the economic benefits should not come at the cost of ecological degradation.Originality/valueThe present study is the first to provide a decision support framework for the selection of substation technologies using the hybrid AHP-TOPSIS approach. It also provides a cost–benefit analysis with short-term and long-term horizons. It further pinpoints the environmental issues with the installation of substation technology.

Reliability analysis of failure threshold value with uncertain Liu process1

A system undergoes a failure process in which the internal degradation and external loads are independent and compete with each other. In the reliability model of competitive failure, the threshold of failure is often a dynamic process that changes with time. Based on this, this paper constructs a model in which the failure threshold is an uncertain Liu process and applies it to the competitive failure reliability process, where soft and hard failure thresholds are modeled by different Liu processes. In the absence of a large amount of failure data, uncertainty theory is used as a tool to analyze the belief reliability and mean time to failure of the system. Taking gas-insulated substation (GIS) as an example, the effect of parameters on belief reliability is analyzed, and the reliability under Liu process threshold and constants threshold is compared, which shows the validity of the prosed model.

Anti-crosstalk magnetic field method for straight-light path type optical current transducer based on the background of gas-insulated substation

Anti-crosstalk magnetic field method for straight-light path type optical current transducer based on the background of gas-insulated substation

Optimization of Electrode-Spacer Arrangement Using Simplex Algorithm

The present article presents the optimization of electric stress distribution over the live electrode of an axisymmetric electrode-spacer arrangement that is used in a Gas insulated substation (GIS) typically for 12–420 kV operations. The technique is based on a classical approach employing Simplex Algorithm which is used to solve constrained linear programming problems (LPPs). For this purpose, the objective function is obtained by applying multiple linear regression analysis by which a mathematical relationship between the maximum resultant electric stress <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$({E}_{\text {max}}^{R})$ </tex-math></inline-formula> over the surface of the live electrode and the critical dimensions affecting this stress. For this purpose, a set of 71 data is used for building the regression model, which is prepared by varying the critical dimensions within the constraints of the overall dimension of the system and calculating the value of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${E}_{\text {max}}^{R}$ </tex-math></inline-formula> over the surface of the live electrode by employing the indirect boundary element method (BEM).

A Novel Domain Adversarial Graph Convolutional Network for Insulation Defect Diagnosis in Gas-Insulated Substations

The data-driven models have achieved remarkable advancements in diagnosing gas-insulated substation (GIS) insulation defects on specific massive datasets. However, restricted by field operating conditions and sample scarcity of GIS, the above methods are difficult to achieve high-precision and robust diagnosis of GIS insulation defects on-site. To settle these problems, we propose an innovative domain adversarial graph convolutional network (DAGCN) for few-shot GIS insulation defects on-site. To improve the accuracy of GIS insulation defects diagnosis, a graph convolutional network (GCN) with multiple attention mechanisms is constructed to take advantage of node features and topology to adaptively mine defect features. Then, a novel domain adversarial (DA) tactic is introduced for GIS insulation defect diagnosis in few-shot conditions through the transfer of diagnostic knowledge. In the proposed DA, the source and target domains classifier loss are jointly optimized to realize feature migration and domain matching. Experiment results demonstrate that the DAGCN achieves reliable diagnosis of GIS insulation defect, which has obvious advantages over existing methods. Simultaneously, the DAGCN proposed can achieve satisfactory diagnosis including unlabeled field samples. Moreover, it has development potential in diagnosing unlabeled samples, thus providing a feasible solution for GIS insulation defect diagnosis and GIS operation and maintenance.

Book Reviews [6 books reviewed

The following six books are reviewed: Gas Insulated Substations, 2nd Edition (Koch, H.J; 2022; Digital Twin Driven Service (Tao, F., et al; 2022); Space Micropropulsion for Nanosatellites—Progress, Challenges and Future (Cheah, K.H.; 2022); Bismuth-Based Materials for Environmental Remediation (Nayak, A.K.;2022); Technologies for Integrated Energy Systems and Networks (Graditi, G. and Di Somma, M.;2022); and Essentials of Semiconductor Device Physics (Martins, E.R.; 2022).

Implementation of Radiation and Soil Losses in VFTO Simulation by Frequency-Domain TL Model

Transmission line (TL) models are widely used within the simulation of the very fast transient over-voltages (VFTO) for gas-insulated substations (GISs); however, due to quasi-TEM approximation and model complexity, energy losses related to bushing radiation and frequency-dependent soil parameters are either not available or simply neglected, limiting the simulation accuracy of TL models. In this study, a new frequency-domain TL model is proposed, enabling the model to consider the influences of both radiation and soil losses in a VFTO simulation. Derived from the radiation power of a line antenna model, the radiation resistance of a “lossy” TL is put forward as an equivalent of the radiation loss for GIS bushing. For the soil loss, the Sunde approximation formula and the L-S soil dispersion expression are involved, and the parameters of the overhead busbar are also analyzed. The model gets validation by the measured VFTO generated at a full-scale 1100 kV GIS testing circuit. By considering radiation loss to suppress high-frequency response and soil loss to improve low-frequency response accuracy, the calculated and measured waveforms have the best consistency, which may greatly help assess the risk of insulation breakdown and the level of very fast transient disturbance in GISs.

Capture Mechanism and Optimal Design of Micro-Particle Traps in HVAC/HVDC Gas Insulated Equipment

Gas-insulated equipment such as GIS (Gas-Insulated Substation) and GIL (Gas-Insulated transmission lines) faces critical insulation failure challenges caused by particles inside. However, the particle traps, as key devices available to inhibit the movement of particles, lack theoretical basis and quantitative methodology for trap design especially with high voltage ratings. In this paper, a particle motion excitation and observation platform is established to physically simulate the actual online operating conditions of HVAC/HVDC GIS/GIL and study the capture mechanism of particle traps. Experimental results illustrate that, the collision motion style is a principal factor to affect the particle capturing capability, and the capture behavior of AC and DC particle traps can be classified into three separate modes, depending on variation of the collision process which can be characterized by random probability and the lognormal distribution rebound angle. A particle trajectory simulation model incorporating motion randomness is thereby presented to realize quantitative analysis and further optimize the trap parameters. A hazard index and minimum collision times are defined and calculated to quantitatively evaluate the particle collision effect on trapping capability. Further, a novel trap design topology is proposed to enhance the anti-motion efficiency of the particle traps. Targeted at high objective capture probability, the particle trap parameters are optimized to reduce the hazard index and improve the minimum collision times by the Monte Carlo scheme. The obtained results indicated that, the capture probability of AC traps can reach 86.5% at a gap spacing of 5 mm, while that of DC traps can reach 74.1% with an 8 mm-width slot and a 50-degree inclination angle. Verification of the novel article trap is implemented on a test rig, which gives an increased capture probability by 30% compared with the traditional trap design. The proposed new trap topology and corresponding methodology present quantitative guidance for particle traps optimization and render application potential for different voltage levels.

Very fast transient overvoltage calculation and evaluation for 500‐kV gas insulated substation power substation with double circuit and long gas insulated substation busbar

The operation of disconnectors in gas insulated substation (GIS) or power plant will produce very fast transient overvoltage (VFTO), which is considered to have serious harm to transformer longitudinal insulation and other high-voltage equipment insulation. VFTO may also lead to secondary circuit failure. In this paper, the holistic modelling of 500 kV GIS step-up substation equipment with a double circuit and long GIS busbar in a coastal power plant is established using Electromagnetic Transient Program (EMTP). The authors calculated the VFTO waveform that may be generated in different operations of the GIS substation. The authors analyze the amplitude and frequency characteristics of the VFTO waveform at lightning arresters and the entrance of transformers and find that the amplitude of VFTO at the entrance of #1 MT is less than its impulse withstand voltage. In some cases, the VFTO waveform at the entrance of #1 MT has high-frequency content with fast attenuation. The VFTO waveform generated when operating the disconnector close to the arrester will cause the arrester to act many times and count frequently in a short time.

Research on VFTO Simulation Analysis of 1000 kV GIS Test Circuit Considering Dynamic Arcing Model

In the research process of very fast transient overvoltage (VFTO), the accuracy of the switching arc model largely determines the calculation results of VFTO. How to more accurately simulate the arc striking and extinguishing process of the arc during the action of the disconnector is the key issue in the study of the arc model. In this article, the ATP-EMTP electromagnetic transient program was used to simulate arc damping with a series connection of a fixed-value resistance and a time-varying inductance, and the built-in MODELS module was used for programming to simulate the reignition and extinguishing process of the arc based on the gaseous dielectric theory and the energy balance theory. The model was applied to a 1000 kV gas insulated substation (GIS) test circuit. The relationship between the arc damping and arc voltage and current was analyzed, and the arc reignition law during opening and closing is studied. The arcing law obtained is compared with the experimental results of the existing literature, and the accuracy of the simulation model is verified. Simultaneously, the influence of the opening speed of the disconnector on VFTO was analyzed by simulation. The results show that when the opening speed is less than 0.7 m/s, the maximum value of VFTO in the test circuit increases with the increase in opening speed. After the VFTO amplitude reaches the maximum and continue to increase the opening speed, the VFTO amplitude decreases. This law is consistent with the experimental results of the existing literature, which proves that the arc model built in this article has a certain engineering application value.