High Voltage Gas Insulated Switchgear Research Articles

Modularization of High Voltage Gas Insulated Substations

Many existing petrochemical facilities are replacing outmoded high voltage (HV) air insulated switchyards (AISs) with new gas insulated switchgear (GIS) substations. Modularization or prefabrication has strategic advantages over site-built substations. While medium voltage (MV) and low voltage (LV) substations have been modularized for many years, the HV GIS substation modularization has not caught up with the construction industry. The modularized HV GIS substations are significantly different compared to other electrical MV or LV substations. This article addresses the modern philosophy and approach to modularization and how the end-user can benefit, in terms of design flexibility, cost-effectiveness, reduced lead times, premium quality, and accelerated site execution in a new or an operating facility. It describes the technological developments, design concepts, quality assurance, and environmental impact in delivering complete solutions based on site conditions.

Seismic performance evaluation of 72.5 kV GIS for design verification (I) - Seismic test

Gas insulated switchgear (GIS) is one of the key components of power transmission and distribution (T&D) systems for providing stable electrical power. Even in the event of a disaster such as an earthquake, the electrical power system should maintain structural safety without losing inherent function. In this study, seismic performance evaluation for 72.5 kV high voltage GIS was conducted using the analysis method. As the first step, a seismic analysis for 1 bay of GIS was done and the analysis model was updated by comparing with the test data like natural frequencies, acceleration and stress. Next step, a seismic analysis of whole GIS of the substation was conducted for seismic performance evaluation according to the IEEE standard. The calculated stress from the analysis compared with the allowable stress and the analysis was repeated until satisfying the criteria after changing the design. Several design changes were made during this process. As a result, the seismic performance of this 72.5 kV GIS of the substation was certified according to IEEE Std. 693-2005.

Application of X-Ray Inspection for Ultra High Voltage Gas-Insulated Switchgear

Owing to the strong penetration ability of X-rays and the imaging visibility, X-ray inspection has been gradually applied to power grids. However, various problems occur in the promotion and application of X-ray inspection in ultra high voltage gas-insulated switchgear (UHV GIS) owing to its large size. These problems relate to parameter selection, photography, protection area, random defect recognition, and risk assessment based on the X-ray image. In this paper, an X-ray digital imaging system is set up for UHV GIS inspection. Parameter selection for UHV GIS is discussed, and we demonstrate that UHV GIS can be photographed under a source-to-detector distance (SDD) of 2.8 m, a tube voltage of 300 kV, and an exposure of >240 mA·s. A photographic method for UHV GIS, entailing adjustment of the position of the imaging plate with a fixed position of the X-ray generator, is proposed to reduce the difficulty in image stitching. The influence of the parameters on imaging quality is discussed, and we show that the brightness and contrast increase with increasing exposure or decreasing SDD. The interactions between parameters are qualitatively introduced. Moreover, the sensitivity of X-ray inspection in UHV GIS is studied under selected parameters, and the sensitivity of X-ray inspection to copper particles and aluminum particles in UHV GIS are shown to be <0.7 mm and <1.1 mm, respectively. Radiation protection for operators is also discussed. In addition, a pseudo-color scheme for identifying random tiny defects is proposed to reduce human error. Finally, the risk level of defects with X-ray inspection is defined by size feature.

Simulation and experimental study on mechanical performance of UHV GIS spacer in hydrostatic test

Gas insulated switchgear (GIS) spacer is required to be of good electrical and mechanical properties to ensure high safety and reliability. The requirements are stricter for ultra high voltage (UHV) GIS spacer under higher voltage and pressure. In previous studies, the insulation characteristics of GIS epoxy spacer were investigated. But researches on the mechanical properties of the GIS spacer were rarely reported. In this study, UHV GIS spacer in hydrostatic test is simulated with the finite-element method. Strain and stress distributions along spacer surface are investigated. Results indicate that the maximum stress appears on the spacer surface near flanging ring, where cracks usually occur. Based on the calculation results, fiber Bragg grating (FBG) sensors are placed on UHV GIS spacer surface to monitor the strain variation in hydrostatic test. Measured results present a strain distribution similar as calculation results. The calculated failure pressure is consistent with those of tested spacers. The crack initiates in the proximity of sealing groove as predicted in calculation.

Application of a multi-parameter sensor system for monitoring dielectric insulation of gas mixtures

The high global warming potential of SF6 motivates the search for eco-friendly dielectric insulation gases. Perfluorinated ketones (FKs) diluted in a carrier gas were recently found to have dielectric properties acceptable for application in high and medium voltage gas-insulated switchgear (GIS). Pilot installations equipped with FK-based insulation gas mixtures are already in operation as this new type of SF6 alternative is approaching maturity for market introduction. SF6 alternatives are generally based on mixtures of gases. An accurate monitoring system for measuring the concentration of FK is desirable because the insulation performance is a function of its composition. We identified a robust and low-cost method for deriving the concentration in a binary gas mixture employing simultaneous measurement of pressure, temperature and density. We have tested two embodiments of this scheme using commercially available sensors. For both, a relative accuracy of better than 4% of the FK content was achieved. A long-term campaign in which an operating outdoor GIS filled with FK-based insulation gas was tracked showed that the measurement is suitable for field environments. The universality of the method and its easy realization with off-the-shelf equipment is of value for any application requiring concentration tracking of binary gas mixtures.

SiO&lt;sub&gt;2&lt;/sub&gt;와 Al&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;3&lt;/sub&gt;를 충진재료로 사용하는 초고압 GIS용 에폭시 절연물 베리어의 전기적 및 기계적 특성에 관한 연구

Abstract: Some insulating materials are organized and analyzed with variables to obtain the optimized profile of encapsulated three phase of epoxy barrier which is applied to gas compartment and supporting conductors for high voltage GIS (gas insulated switchgear). The high voltage GIS is used in electrical power system and operating reliability. In this paper, optimization possibility of barrier shape including both electrical insulation performance and mechanical strength, premised on that condition minimizing volume and light weight should be kept for high voltage GIS, could be achieved by analysis simulation. As a result, filling material which is lower permittivity such as SiO 2 instead of Al 2 O 3 properly to the epoxy material, can be improved to increase the electrical insulation performance and mechanical strength for an optimized profile barrier of a high voltage GIS. Keywords: High voltage GIS, Barrier, Enclosure, Epoxy, SiO 2 , Al 2 O 3 , Filler, SF 6 , Electric field, Permittivity1. 서 론

A Novel Arc Model for Very Fast Transient Overvoltage Simulation in a 252-kV Gas-Insulated Switchgear

One of the important issues of concerns for gas-insulated switchgear (GIS) is the generation of very fast transient overvoltage (VFTO) during switching operations, especially at operational voltage levels of 330 kV and beyond. It becomes extremely important to build an arc model for VFTO simulation, since the arc determines VFTO characteristics to a great extent. However, existing arc models for VFTO simulation are too simple to provide simulation results that agree well with the experimental ones. As the arc resistance is often taken as a function of the very fast transient current (VFTC), it is necessary to get the experimental data on the VFTC. Therefore, a 252-kV GIS platform has been built as well as the VFTO and VFTC measuring system. On the basis of the experimental investigation, a novel arc model for VFTO simulation was proposed, in which the time dependent characteristics of the arc resistance is revealed. The model may be used for VFTO simulation for extra high voltage or ultrahigh voltage GIS.

Particle Detector for Gas Insulated Switchgear and the Effect on Environment

High voltage Gas Insulated Switchgear (GIS) is prone to metallic particles. The particle void can reduce the dielectric strength of the insulation material of SF6 gas. This paper discusses the developed particle detector for GIS using a new approach by using image processing to reduce flashover phenomena occurring on energized GIS. The particle detector consists of borescope, laptop and a detection program. The program was coded using MATLAB using image processing algorithm. The in-lab test was conducted on the simulated GIS to see the effectiveness of the particle detector to detect small particles inside the narrow GIS enclosure. In real world application, the borescope will be inserted through GIS access hole before filling the enclosure with SF6 gas. This new approach is proposed to be conducted during the erection and commissioning of new GIS. This new approach looks promising because it can reduce flashover phenomena caused by existence of metallic particle and also reduces Greenhouse gas emission to the air.

Effects of nozzle shape on the interruption performance of thermal puffer-type gas circuit breakers

During the last decade the advanced interruption techniques, which use the arc energy itself to increase the pressure inside a chamber by PTFE nozzle ablation, have displaced the puffer circuit breakers due to reduced driving forces and better maintainability. In this paper, we have investigated thermal flow characteristics inside a thermal puffer-type gas circuit breaker (GCB) by solving the Navier–Stokes equations coupled with Maxwell's equations for considering all instability effects such as turbulence and Lorentz forces by transient arc plasmas. These relative inexpensive computer simulations might help the engineer researching and designing new advanced interrupters in order to downscale and uprate high-voltage gas-insulated switchgear (GIS) integral.

05/00150 Thermo-characterization of power systems components: a tool to diagnose their malfunctions: Zaleta-Aguilar, A. et al. Energy, 2004, 29, (3), 361–377

During the last decade the advanced interruption techniques, which use the arc energy itself to increase the pressure inside a chamber by PTFE nozzle ablation, have displaced the puffer circuit breakers due to reduced driving forces and better maintainability. In this paper, we have investigated thermal flow characteristics inside a thermal puffer-type gas circuit breaker (GCB) by solving the Navier–Stokes equations coupled with Maxwell's equations for considering all instability effects such as turbulence and Lorentz forces by transient arc plasmas. These relative inexpensive computer simulations might help the engineer researching and designing new advanced interrupters in order to downscale and uprate high-voltage gas-insulated switchgear (GIS) integral.

Gas-Insulated Switchgear and Interrupter

The historical progress of gas-insulated equipment in Japan is reviewed and the trend of technologies is discussed in the present paper. Since gas-insulated switchgear (GIS) and gas circuit breaker (GCB) have been widely applied to substation equipment, advanced technologies for high realiability and compactness of GIS are still required. Recent progress of analytical technologies, using digital computers, can meet their requirements. Technologies of gas insulation have contributed to the application of the equipment for the power transmission system and been attempted to advance GIS, such as ultra high voltage (UHV) GIS and HVDC GIS, with electronic diagnostic technologies.