Partial Discharge Induced Decomposition Properties and Mechanism of HFO-Butene/CO2 as Eco-Friendly Gas Insulating Medium

HFO-butene [HFO-1336 mzz(E)] has been explored as an eco-friendly gas-insulating medium to replace the most greenhouse gas sulfur fluoride (SF6) for the power industry. At present, studies on the stability and decomposition mechanism of HFO-butene mainly focus on neutral molecules or radicals. However, the discharge-induced decomposition will generate positive and negative ions, which significantly affect the physicochemical properties of gas composition. Meanwhile, experimental evaluation of the partial discharge (PD) induced decomposition characteristics of HFO-butene is lacking. In this article, the decomposition mechanism of HFO-butene considering free radicals and ions is systematically explored for the first time. The molecular structure, ionization, and attachment properties of HFO-butene are revealed, and the reaction enthalpy analysis of the decomposition and by-product generation pathways are explored. The long-term PD experiments on HFO-butene/CO2 gas mixture are conducted combined with gas composition analysis under different applied voltage, gas pressure, and mixing ratio conditions. Relevant results provide an important reference for understanding the PD decomposition characteristics of HFO-butene.