Abstract:

The malfunctioning of SF₆ gas density monitoring in GIS equipment could erroneously indicate a leakage, potentially compromising the electrical grid's safe operation. In response, a thermodynamics-based temperature hysteresis model for SF₆ gas was developed and refined, tailored for digital gas density monitoring apparatus. The model's unknown parameters were deduced from temperature hysteresis experiments. The simulations highlighted a temperature compensation deviation in the SF₆ gas temperature hysteresis model of ±0.6 ℃, with a pressure calculation discrepancy, corrected for temperature, showing only ±0.002 MPa against sensor-detected pressures. A strategic approach for identifying density monitoring failures was devised, which relies on the corroboration between calculated and sensor-detected pressures. This approach was put to the test using data from a pilot device in a 220 kV substation. After applying temperature adjustments through the SF₆ gas temperature hysteresis model and recalibrating the pressure to standard conditions at 20 ℃, the results remained within a tight margin of 0.002 MPa, attesting to the model's precision and the practicality of the proposed SF₆ gas density monitoring failure detection strategy in operational environments.

Key words: SF₆ gas, digital SF₆ gas density monitoring device, monitoring failure determination, temperature hysteresis model