Temperature and composition of AC arc plasma of medium voltage distribution networks in the air

Self Cite

AC air arcs are generated in medium-voltage (MV) power systems under the effect of harsh weather conditions, equipment aging, and high penetration of distributed generation, threatening equipment and public safety. The arc current and temperature are low due to the wide application of arc suppression devices. In this scenario, the MV AC air arc does not satisfy the local thermodynamic equilibrium (LTE) condition. In addition, the repeated arcing and extinguishing processes further complicate the arc discharge mechanism, which bring challenges in the modeling and detection of MV AC air arcs. Experimental methods are a direct and efficient approach to determine the properties of arc plasmas. In this study, a dual-wavelength moiré deflection diagnostic system was established to determine the time evolution of the particle density and radial distribution of the temperature in an MV AC air arc without relying on the LTE assumption. The electron number density and heavy particle number density change transiently during the arc discharge process and change gradient along the radial direction. The heavy particle temperature and electron temperature were then calculated based on the measured particle number density. During the arcing stage, the temperature of the electrons exceeded that of the heavy particles significantly, and the arc deviated from LTE. Finally, the limitations of the traditional single-wavelength moiré deflection method are analyzed. The classic single-wavelength moiré deflection method, while capable of estimating heavy particle temperature in plasma, exhibits a significant error in electron density estimation compared to the dual-wavelength moiré deflection method.

Section: Refractive Indexmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Measurement of medium-voltage AC air arc temperature and particle number density based on dual-wavelength Moiré deflection technology

Zhou,

Yang,

Yuan

et al. 2024

Self Cite

“…After the detection light (wavelength λ = 405 nm) deflected by the thermal field of the gap passes through the gratings G 1 and G 2 , the Moiré fringes are distorted, as shown in figure 9. The specific parameters of the lens, grating, and laser can be referred from a previous work [29]. The model of the high-speed camera used was Eosens mini2 with a frame rate of 2000 fps.…”

Section: Optical Measuring Unitmentioning

confidence: 99%

Plasma characteristics of medium voltage AC air arc discharge and its application on arc electrical parameters calculation

Zhou,

Yang,

Yuan

et al. 2023

Self Cite

Medium Voltage (MV) AC air arcs occur frequently in distribution networks. An electric arc can easily cause electrical fires, leading to serious accident consequences. Obtaining the electrical characteristics of arc faults through arc models is a crucial measure to detect and prevent arc faults. The arc electrical characteristics are affected by many factors such as the ambient air pressure, current magnitude, and arc length, and it is difficult to describe it in an analytical form. The widely used conventional black-box arc model reflects the influence of multiple factors on the electrical characteristics of arcs through fitting or empirical formulae. The model ignores the intrinsic physical and chemical processes, and the applicable range of the model is limited. Focusing on this problem, based on the physicochemical processes of the arc in the arcing and post-arcing stages, a relationship between the electrical and plasma characteristics of the MV AC air arc was established. Subsequently, the arc plasma characteristics were determined experimentally, and were applied to the calculation of the arc electric characteristics. Finally, the calculation results of the arc electrical characteristics were verified using the experimental results, providing a basis for related model improvements and applications.

“…However, due to mechanical oscillation, the pantograph strip may detach from the catenary line and PC arc appear [4], which threats to power supply of electrified railways [5][6][7]. For example, arc plasma can damage the pantograph strip and catenary line, and may get close to supporting insulators under the influence of airflow, resulting in short-circuit discharge [8,9]. The damage caused by the arc is closely related to its dynamic characteristics, such as arc column motion range and arc root jumping behavior.…”

Section: Introductionmentioning

confidence: 99%

Research on driving force and dynamic characteristics of pantograph–catenary arc

Qian

Gao

Dong

et al. 2023

pantograph-catenary(PC) system is the key current collection equipment for electrified rail vehicles. The PC arc aging the contact line and pantograph abnormally, which is a limiting factor for rail transit to increase the speed of operation. To reduce the harm caused by PC arc, in this article, a new PC arc chain model was established, which considered the arc current element mass and the acceleration process, updating control equations. Meanwhile, a PC arc experimental platform was built in order to verify this model. It is demonstrated that the simulation results by this work fit the arc and is suitable to describe the arc in field. Experiments have found that the evolution of PC arc can be divided into three distinct processes: arc initial process, rapid stretching process and violent oscillation process. Combined with the model, the driving force and dynamic characteristics of the PC arc root and column in each process have been studied. The electromagnetic force dominates the arc evolution in first two processes, then the wind load dominates the last process. Besides, thermal buoyancy dominates arc root jumping behavior. The driving mechanism for the movement of arc has been revealed. The arc root first suppresses the arc column, and then the arc column pulls the arc root. It is helpful for controlling of PC arc in field.