Electrical Circuit Flashover Model of Polluted Insulators under AC Voltage Based on the Arc Root Voltage Gradient Criterion

Abstract

Abstract:In order to study the flashover mechanism of polluted insulators under AC voltage, a new arc propagation criterion which is based on an arc root voltage gradient is proposed. This criterion can explain the variation of the arc root voltage gradient in the arc propagation process. Based on this criterion, a new distributed parameter electrical circuit flashover model of polluted insulators is presented. The arc channel is considered as an equivalent distributed parameter circuit model instead of using the arc voltage-gradient equation. The parameters of the arc model are obtained from the electromagnetic field distribution of the arc and the gas discharge theories. The arc root is considered as parallel paths including the polluted layer. The variation of the voltage on the arc root is related to the capability of arc propagation. This model takes the microscopic mechanism of arc root ionization into consideration, which can improve the accuracy of the flashover model. The results obtained from the presented model are in good agreement with other mathematical and experimental results.

Voltage Distribution and Flashover Performance of 220 kV Composite Insulators under Different Icing Conditions

“…The detailed test procedure to determine U50 is shown in [23,29]. Provided that N is the number of test results, the first flashover voltage is marked with U1, the second one U2,and the Nth Un, U50 can be expressed as: In the existing studies, the voltage distributions of the iced insulators were obtained by simulations [19][20][21], but the simulated results have not been validated by experiments.…”

“…The detailed test procedure to determine U 50 is shown in [23,29]. Provided that N is the number of test results, the first flashover voltage is marked with U 1 , the second one U 2 ,and the Nth U n , U 50 can be expressed as:…”

A new proposed dynamic arc model for flashover performance of a non-uniform polluted insulator string under HVAC stress

“…The oscillograms also reveal that the leakage current has shown a strong fundamental component with little or no harmonics under normal conditions whereas under arcing conditions the harmonic content increases. Numerous publications [21][22][23][24] attribute this behavior to a flashover process that is nonlinear and predominantly random in nature; the surface discharges are nonlinear arcs, the Fig. 7.…”

Ion Migration in the Process of Water Freezing under Alternating Electric Field and Its Impact on Insulator Flashover

“…According to Equations (3)-(5) and analysis above, accurately calculating the surface conductivity of ice layer formed in energized condition is very important for accurately predicting flashover voltage of ice-covered insulator. References [33,34] provided a linear fitting equation which was often used to calculate the equivalent surface conductivity of ice layer. The ice sample in References [33,34] formed in the triangular glass mould was not under electric field, that is, it ignored the effect of alternating electric field during the icing process.…”

“…References [33,34] provided a linear fitting equation which was often used to calculate the equivalent surface conductivity of ice layer. The ice sample in References [33,34] formed in the triangular glass mould was not under electric field, that is, it ignored the effect of alternating electric field during the icing process. However, the experimental data in Sections 3 and 4 of this paper showed that electric field did have an effect on the conductive ion distribution of ice layer.…”