Gas Insulated Switchgear System Research Articles

Multi-source domain adaptation network for partial discharge severity assessment in gas-insulated switchgear

Abstract Gas-insulated switchgear (GIS) partial discharge (PD) severity assessment is critical for ensuring the reliable operation of GIS systems. However, existing assessment methods often overlook the long-term dependencies of historical data and fail to adequately address challenges related to limited on-site samples and variations in sample distribution. To overcome these challenges, we propose a novel multi-source domain adaptation network (MSDAN) specifically designed for on-site GIS PD severity assessment, which is the first model developed considering distribution differences in GIS PD severity assessment for different defect types. Our approach begins with the development of a feature extractor that captures both discernible PD features and long-term dependencies. We then introduce a multi-source domain adaptation strategy to mitigate distribution disparities across PD severity samples from different defect types, ensuring effective domain alignment. Additionally, we incorporate an adaptive weighted classification mechanism to accurately assess PD severity by considering the varying contributions of different defect types to the target domain task. Experimental results demonstrate that MSDAN achieves a remarkable accuracy of 95.38% in on-site GIS PD severity assessment, outperforming other benchmark models in both accuracy and robustness. This highlights the potential of MSDAN as a robust solution for real-world GIS PD severity assessment.

Simulation Study on Mechanical Vibration Characteristics of GIS Bus Misalignment

Abstract Gas-insulated switchgear (GIS) has been widely used in power grid systems. The busbar is a crucial element within a GIS system, responsible for facilitating electrical connections between different GIS components. Any defects during manufacturing or improper installation procedures can lead to busbar misalignment, resulting in abnormal vibrations within the GIS. This study focuses on analyzing the mechanical vibration characteristics of GIS bus misalignment using a simulation model based on the finite element method for a 252kV GIS. When the busbar is misaligned and the conductor experiences an unbalanced force, it undergoes Coulomb forces at double the voltage frequency. Under normal or misaligned conditions, the conductor exhibits forced vibrations at the power frequency of 100Hz. However, when misalignment occurs, there is a coupling effect between electrodynamics and vibrations, causing the shell to display integer frequency vibration components.

Fault Diagnosis in Gas Insulated Switchgear Based on Genetic Algorithm and Density- Based Spatial Clustering of Applications With Noise

As a kind of widely used switchgear in power system, the reliability of gas insulated switchgear (GIS) is very important for the safe operation of power systems. However, there is a lack of research on intelligent detection technology of mechanical state of GIS at present. A new method is urgently needed to improve the operability, effectiveness, and accuracy of fault detection in GIS. Aiming at the abnormal vibration signals generated by GIS faults, this article presents a fault diagnosis method (GA-DBSCAN) consisting of a feature selection method based on genetic algorithm (GA) and Density-Based Spatial Clustering of Applications with Noise (DBSCAN), and a fault diagnosis method based on DBSCAN. First, this article analyzes the incentive force of GIS and discusses the characteristic frequency of response signal combining with the non-linear characteristics of a GIS system. Second, GA and DBSCAN are used to screen features for dimension reduction and get the optimized feature space, and DBSCAN-based classification is used to classify faults. Finally, optimized feature space is verified to be superior to the original feature space by typical classification method; the superiority and reliability of DBSCAN-based classification method under optimized feature space is verified by comparing with other classification methods. The proposed GA-DBSCAN approach can substantially increase the performance of the fault diagnosis method, which indicates that the method promotes development of intelligent detection technology of mechanical state in GIS.

PD Signal Attenuation in 550-kV GIS: Impact of Different Barriers on the Propagation of Electromagnetic Waves

Accurate modeling of partial discharge (PD) within gas-insulated switchgear (GIS) has become of paramount significance to improve the utilization of ultrahigh frequency (UHF) sensors within such capital assets. Providing better insight on how electromagnetic (EM) waves propagate within GIS systems provides valuable information that can be used to determine the optimal allocation of UHF sensors. Thus far, most existing models are not considering the full complexity of the GIS systems due to the many associated challenges and the high computational demand of such system modeling. In this work, a GIS system is modeled using the Maxwell solver of COMSOL multiphysics. CIGRE sensitivity verification recommendations (CSVR) are used to inject UHF signals using an internal sensor. Then, two external sensors, placed on the outer belt of dielectric spacers, are used to capture the radiated EM waves. The electric field distribution at selected frequencies is presented and discussed under two operating conditions for disconnecting switches. The modeled GIS contains many barriers, including two bends, multiple sudden changes in the outer to inner diameters ratios, six dielectric spacers, and two disconnecting switches. Time-domain simulation results are also presented to provide an insight into the attenuation properties of EM waves due to the different barriers. Finally, a comparison between simulated and measured results has been carried out to verify the modeling accuracy. The results show that GIS systems form complex structures for the EM waves, and fully understanding the wave propagation can be tedious.

Effects of SF6 decomposition components and concentrations on the discharge faults and insulation defects in GIS equipment

Gas-insulated switchgear (GIS) is widely used across multiple electric stages and different power grid levels. However, the threat from several inevitable faults in the GIS system surrounds us for the safety of electricity use. In order to improve the evaluation ability of GIS system safety, we propose an efficient strategy by using machine learning to conduct SF6 decomposed components analysis (DCA) for further diagnosing discharge fault types in GIS. Note that the empirical probability function of different faults fitted by the Arrhenius chemical reaction model has been investigated into the robust feature engineering for machine learning based GIS diagnosing model. Six machine learning algorithms were used to establish models for the severity of discharge fault and main insulation defects, where identification algorithms were trained by learning the collection dataset composing the concentration of the different gas types (SO2, SOF2, SO2F2, CF4, and CO2, etc.) in the system and their ratios. Notably, multiple discharge fault types coexisting in GIS can be effectively identified based on a probability model. This work would provide a great insight into the development of evaluation and optimization on solving discharge fault in GIS.

Vibration Feature Analysis for Gas-Insulated Switchgear Mechanical Fault Detection under Varying Current

As a key component to ensure the safe operation of the power grid, mechanical defect diagnosis technology of gas-insulated switchgear (GIS) during operation is often neglected. At present, GIS mechanical fault detection based on vibration information has not been developed. The main reason is that the excitation current is considerable but uncontrollable in the actual operation of GIS. It is difficult to eliminate the influence of excitation on the vibration amplitude and form an effective vibration feature description technology. Therefore, this paper proposes a unified feature-extraction method for GIS vibration information that reduces the influence of current amplitude for mechanical fault diagnosis. Starting from the GIS mechanical analysis, the periodicity of vibration excitation and the influence of amplitude are discussed. Then, combined with the non-linear characteristics of GIS systems and non-linear vibration theory, the multiplier frequency energy ratio (MFER) is designed to extract vibration-unified features of GIS for diagnosing the mechanical fault under different current levels. The diagnosis results of the experimental data with different feature-extraction methods show the applicability and superiority of the proposed method in the GIS’s mechanical fault-detection field based on vibration information.

Study on Very Fast Transient Overvoltage of Closing No-load China UHV Transmission Demonstration Project Jindongnan-Nanyang-Jingmen 1000 kV Transmission Lines

When the ultra high voltage (UHV) substation used the gas insulated switchgear (GIS) system to switch lines with capacitive current, the pre-breakdown and multiple reignition will occur between switching contacts. Because of discharge characteristics of SF6 and special structures of GIS system, the variations of the electromagnetic transient process and very fast transient overvoltage (VFTO) are very fast and extremely complex. The development process and characteristics of VFTO remain to be dealt with to seek effective suppression measures. The overvoltage of closing no-load long lines on GIS system is analyzed in detail. The simulation model of the very fast transient process of closing no-load long lines on UHV GIS system is established. The VFTO of closing no-load China UHV transmission demonstration project Jindongnan-Nanyang-Jingmen 1000 kV transmission lines is analyzed using electromagnetic transient simulation software ATP-EMTP. The VFTO of closing no-load long lines on UHV GIS system is simulated and calculated, when the system has no additional closing resistors and lightning arresters, additional single stage closing resistors, additional multistage closing resistors, lightning arresters in two terminals of lines, lightning arresters in two terminals and the middle of lines, and additional multistage closing resistors and lightning arresters in two terminals and the middle of lines. The simulation results show that the additional multistage closing resistors and lightning arresters in two terminals and the middle of lines can effectively restrain the VFTO of closing no-load long lines on UHV GIS system.

APPLICATION OF COMBINED CURRENT AND VOLTAGE SENSOR FOR PROTECTION AND METERING IN GIs SYSTEMS.

Gas insulated switchgear (GIS) is an ideal system for installations in a limited space, if a high availability is required. The new combined sensors are a perfect base for a wide range of applications in protection, metering and control in the field of gas insulated substations. The two most important functions performed in this combined sensor are the measurement of current and voltage for protection, metering and conrrol. The principle of Regowski coil is used for current measurement and of the capacitive voltage divider for voltage measurement. Signals are converted to digital values and forwarded through fiber optical cable to local control cubicles. This data acquisition is an important part of an intelligent control and protection technique for GIS system. This paper describes the design of a combined sensor, block diagram and Accuracy features of such sensors. Good properties of the sensor permit its use for measurement, protection and control. Moreover, insulating gas density and temperature, also enables evaluating and recording the signals. The simple layout of this combined sensor significantly improves dielectric capability in comparison with conventional designs. Measuring techniques have been developed to asses and improve measuring and dynamic accuracy. Results show that the combined sensor is of better quality than known for conventional inductive instrument transformers. Combined current and voltage sensors for GIs fulfill the requirements for protection, metering and control which add several advantages for the user.