Equivalent energy storage model coupled electromagnetic wave energy safety analysis of metal structures in underground coal mines

The electromagnetic wave energy emitted by wireless communication equipment in coal mines can be coupled and absorbed by surrounding metal structures, which poses a risk of igniting explosive gases in the mine. The existing research on the safety of underground metal structure coupled electromagnetic waves only focuses on the analysis of the energy of metal structure equivalent impedance model coupled electromagnetic waves. It lacks research on the energy storage process of metal structure coupled electromagnetic wave energy accumulated over time. In order to solve the above problems, an equivalent energy storage structure model suitable for studying the coupling-accumulation-release electromagnetic wave energy of metal structures is proposed, namely the metal structure equivalent capacitive energy storage model and the metal structure equivalent inductive energy storage model. Firstly, by using a low attenuation transmission line model, the relationship between the output power of the transmitting antenna, the distance between the transmitting antenna and the metal structure, and the induced voltage at the receiving end is derived. Secondly, an equivalent energy storage model of metal structure is established. The mathematical relationship between the receiving end parameters and the discharge spark energy is derived. The influence of the receiving end parameters on the discharge spark energy is analyzed. Finally, the mathematical relationship between the output power of the transmitting antenna, the distance between the transmitting antenna and the metal structure, and the discharge spark energy is derived by analyzing the relationship between the induced voltage at the receiving end and the effective value of the induced voltage. The influence of the output power of the transmitting antenna and the distance between the transmitting antenna and the metal structure on the discharge spark energy is analyzed. The theoretical reference safety points of the equivalent energy storage models of the two metal structures are given under the condition of other parameters being determined. The simulation results show the following points. ① For the equivalent capacitive energy storage model of metal structures, the discharge spark energy increases with the increase of the effective values of the equivalent energy storage capacitor and the induced voltage at the receiving end, and the safety point shifts to the left. The safety requirements for the effective values of the equivalent energy storage capacitor and the induced voltage at the receiving end become stricter. ② The energy of the discharge spark increases with the increase of the transmitting antenna power, and decreases with the increase of the distance between the transmitting antenna and the metal structure. The theoretical reference safety point of the equivalent capacitive energy storage model of the metal structure is obtained. ③ For the equivalent inductive energy storage model of metal structures, the discharge spark energy increases with the increase of the effective values of the equivalent energy storage inductance and the induced voltage at the receiving end, and the safety point shifts to the left. The safety requirements for the effective values of the equivalent energy storage inductance and the induced voltage at the receiving end become stricter. ④ The energy of the discharge spark increases with the increase of the transmitting antenna power, and decreases with the increase of the distance between the transmitting antenna and the metal structure. The theoretical reference safety point of the equivalent inductive energy storage model of the metal structure is obtained. ⑤ Comparing the theoretical reference safety points of two metal structure energy storage models, it is concluded that the danger of the metal structure equivalent capacitive energy storage model is much greater than that of the metal structure equivalent inductive energy storage model.