A Method to Construct Early-Warning and Emergency Response System for Sulfur Hexafluoride Leakage in Substations

Abstract

Sulfur hexafluoride (SF 6) gas leakage in populous urban areas, once occurring, can cause death from suffocation if its concentration largely exceeds 1000ppm and oxygen concentration is low than 19 vol-%. Leakage that cannot be detected and responded to with prompt and effective measures can even lead to large death tolls. Presently, few systematic technical approaches to monitoring, early-warning, consequence prediction, and emergency response of SF 6 leakage have been reported. In this paper, a method for constructing the early-warning and emergency response system for SF 6 leakage in substations is proposed. Firstly, the concentration distribution of leaked SF 6 gas at different leakage points within the substation space is analyzed using CFD simulation to determine the coordinates of sensitive areas where the exceeding of the threshold value of SF 6 concentrations is first detected and thus to ascertain sensor monitoring points. By altering leakage locations and leakage orifice diameters within the substation space, the data concerning the coupling relationship between leakage time, leakage orifice diameter, and concentration are obtained, and a prediction model of diffusion concentration of SF 6 leakage in substations is established through regression. Based on the prediction model, an emergency response system for SF 6 leakage in substations is constructed; additionally, in combination with safety management data of substations, the files required for emergency responses to SF 6 leakage can be identified immediately after occurrence, which provide a guidance for on-field personnel to take emergency responses and safety prevention measures. In this paper, a case study of a substation leakage event is presented to describe the method to construct an early-warning and emergency response system for leakage in substations, as well as the application of the method. The results of this research can provide a theoretical basis for early-warning and emergency response to SF 6 leakage, thereby improving the inherent safety levels of substations.

Sulfur Hexafluoride Gas Leakage Monitoring and Early-Warning Method for Electrical Power Facilities

“…7.9, 0.1, 1.5 17 6, 9.9, 1.5 27 7.9, 5, 0.1 37 7.9, 2.5, 0.1 8 7.9, 5, 1.5 18 7.9, 2.5, 1.5 28 7.9, 9.9, 0.1 38 7.9, 7.5, 0.1 9 7.9, 9.9, 1.5 19 7.9, 7.5, 1. Based on the method for determining the sensor points reported in a previously published article [2], the simulation results were used to determine that when a leak occurred at point 1, the sulfur hexafluoride gas concentration first exceeded 1000 ppm at monitoring points 8 and 27 seven times, which was more often than the times that it first exceeded this limit at the other points . When a leak occurred at point 2, the sulfur hexafluoride gas concentration first exceeded 1000 ppm at monitoring points 24 and 32 eight times, which was more often than the times that it first exceeded this limit at the other points .…”

“…Based on the method used for the model in a previously published article [2], a gas leakage monitoring and earlywarning model could be established through regressing and fitting the simulated data [12]- [17], in which the gas leakage orifice diameter was x, leakage time was y, and sulfur hexafluoride gas concentration was z. Table 2 shows the model of monitoring point 24 for a leak occurring at point 1 [2]. The concentration values could be acquired by substituting different values for the gas leakage orifice diameter and leakage time into the model.…”

“…Because of factors such as land shortage, substation construction often involves high-capacity equipment and underground development. Most substations utilize sulfur hexafluoride electrical equipment [1], with a 1000 ppm index used for sulfur hexafluoride gas leakage monitoring [2]. Based on expert knowledge and research results, it can be concluded that once a sulfur hexafluoride gas leak lowers the oxygen concentration to less than 19%, workers and maintenance staff will be exposed to potential asphyxiation.…”