Calculation of Electron and Heavy Particle Temperature with Transient Recovery Voltage Using 3-D Electromagnetic Thermal Fluid Simulation

Abstract

The point of accident must be quickly and reliably isolated when an accident occurs in the power system. For this reason, the improved performance of circuit breaker is required. However, arc is generated between electrodes with interrupting the current. Furthermore, the transient recovery voltage is applied from the power supply after the current is cut off. These physical phenomena are on the order of milliseconds to microseconds. Thus, arc becomes non-equilibrium. It is reported that the thermal non-equilibrium is remarkable in the post arc. This is because the electron is more easily accelerated by the electric field than heavy particle. The electron number density increases with increasing the electron temperature. The increase in electron number density is the cause of re-striking. Thus, it is necessary to elucidate the increase in electron number density with increasing the electron and heavy particle temperature in order to improve the performance of circuit breaker. However, few reports have researched the electron and heavy particle temperature with the transient recovery voltage. This is because it is difficult to measure the microsecond temperature and the low brightness temperature in the post arc. As a countermeasure, the 3-D electromagnetic thermal fluid simulation under consideration of thermal non-equilibrium is useful. In this research, the electron and heavy particle temperature with the transient recovery voltage were calculated using the 3-D electromagnetic thermal fluid simulation. The energy conservation equations for electron and heavy particle were discretized by simulating a three-dimensional space. As a result, the electron temperature increased with increasing the transient recovery voltage. On the other hand, the heavy particle temperature increased from the energy transfer from electron to heavy particle. In addition, the heavy particle temperature at peripheral part decreased from the convective heat transfer. Therefore, the difference of physical phenomena between electron and heavy particle temperature with the transient recovery voltage were elucidated.