Abstract
In ultra HVDC transmission system, arcing horn gap breakdown makes the arc hard to extinguish, threatening transmission safety. Multi-chamber arrester (MCA) is applied in extinguishing the arc to ensure safety. Here, we investigated the arc motion characteristics of the MCA to analyze its arc extinguishing ability. First, a three-dimensional model of the arc plasma in a single chamber was established based on magneto-hydrodynamic (MHD) theory, and the arc motion inside and outside the chamber were analyzed. Next, changes of temperature, velocity and pressure field were simulated. The results showed that the time required for arc totally exiting the chamber is approximately $96~\mu \text{s}$ , the airflow maximun velocity is about 865 m/s, and the highest pressure is more than 4 atm. Particularly, there is a flow reflux at the outlet, as the air flows inward from the outside and form an “oscillation”. Moreover, the arc motion characteristics of different discharge currents within different chamber structure were analyzed. It was found that the spacing between anode and cathode, the radius of electrodes and the outlet radius are the key factors regulating the airflow velocity, and the outlet radius of the chamber has the greatest influence. At last, the accuracy of our model was validated with experimental data.
Highlights
An arcing horn is used to protect insulators of ultra HVDC transmission line from being burned by the arc [1]
The effects of electrical conductivity, temperature, airflow velocity, current amplitude and structural parameters on arc motion in multi-chamber are analyzed [10], but the process in the simulation results is in the order of milliseconds, which is quite different from the experiment results, which is in the order of microseconds
At 80 μs, the arc column is pushed out to the outside of the chamber, and the temperature of the arc column is reduced to 4500 K which was cooled by the air outside the chamber. 4) 96-430 μs: almost all the arc plasma moves integrally to the outside of the chamber and spreads to the periphery
Summary
An arcing horn is used to protect insulators of ultra HVDC transmission line from being burned by the arc [1]. There have been many studies on arc extinguishing measures of arcing horn: using non-linear resistance characteristics of Zinc oxide resistors (MOA) to extinguish arcs [3]; using magnetic field to force the arc to elongate rapidly or to rotate the arc at high speed [4]; making polyvinyl chloride produce gas to blow the arc at high temperature [5], etc These measures have some limitations, such as complex structure, processing difficult, cost expensively, poor reliability, and heavy maintenance workload in the later stage. The effects of electrical conductivity, temperature, airflow velocity, current amplitude and structural parameters on arc motion in multi-chamber are analyzed [10], but the process in the simulation results is in the order of milliseconds, which is quite different from the experiment results, which is in the order of microseconds. Where v × B is 0, σ means conductivity, E means electric field intensity, ρq means charge density, ε0 means dielectric constant
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