37 / 2024-03-29 15:53:15

Research on the Mathematical Model of Cable Single-phase Ground Fault Arc Simplified from MHD Simulation

Single-phase grounding faults,ground fault arc,cable,MHD

Single-phase grounding faults rank as the most prevalent and challenging failures within distribution networks, with arc grounding faults making up the majority of these incidents, especially in three-core cable. Such faults lead to the deterioration of line insulation, posing a significant risk to the power grid’s safe and stable operation. In order to realize the rapid identification of grounding fault in cable distribution network, the arc mathematical model is usually used in simulation of ground fault to guide the effective detection of distribution network fault. Nonetheless, the traditional arc black-box model falls short in accurately portraying the evolution of cable grounding fault arcs, making it less applicable to real fault scenarios. Therefore, this study is to explore a novel mathematical model of ground fault arc, which is simplified from the magnetohydrodynamics (MHD) model for accurate detection of ground faults. In this paper, firstly, according to the geometric structure of three-core cable and the actual ground fault condition, a multi-physics coupling simulation model of single-phase grounding fault is established, as shown in Fig. 1, combined with equations controlled by MHD. Based on the structure of the three-core cable and the location of the arc fault point, the size of stable arc channel is set. The fault ground current is set to be 50 Hz alternating current with RMS value of 150 A. The transient MHD model take the steady-state arcing stage of grounding arc as the initial value. Secondly, the arc-burning phenomenon during the process of single-phase grounding fault is analyzed. The electric potential distribution and temperature distribution of arc plasma are shown in Fig. 2. Thirdly, the characteristic parameters of arc mathematical model are extracted from the simulation results, including arc conductance, arc time constant and heat dissipation power. Subsequently, the function relationship of characteristic parameters is established by fitting, which is used for mathematical model. Finally, the mathematical model of cable single-phase ground fault arc is proposed, as the overall process is shown in Fig. 3. This paper proposes a novel research method of single-phase grounding fault of cable, which can provide an effective criterion for rapid detection and effective diagnosis of faults in distribution network system.