MODELING AC ARC RE-IGNITION CONDITIONS ON ICE -COVERED INSULATORS USING ARTIFICIAL NEURAL NETWORKS
The propagation of local arcs are necessary for a flashover to occur on an ice-covered insulator. It was supposed that the local AC arc extended when it satisfied the arc re-ignition conditions. In this paper an attempt has been made to model Va = f ( I , L , x ) for estimating the arc re-ignition conditions as function of leakage current and insulator length using multi-layer feed-forward neural network with back propagation technique. Once trained with experimental results taken from the CIGELE model , the proposed ANN model is then capable of predicting arc maintenance voltage , under any given set of leakage current and insulator length. With the use of the optimized ANN parameters , a prediction accuracy with a %MAE of 2.85% was achieved.
Propagation of ac and dc arcs on ice surfaces
Using a high-speed camera, the fundamental behavior of arcs on ice surfaces, including propagation velocity and root radii were studied under both ac and dc voltages. It was found that the arc may propagate randomly inside or outside of the ice with a relatively low velocity before the critical length is reached, and then at a much higher velocity. Moreover, the relationship between the radius of the arc root and leakage current was determined. The results obtained allowed us to improve our previous model dealing with insulators. There is a good concordance between the critical flashover voltage of ice-covered insulators calculated from the model and laboratory results.
Discharge performance of different models at low pressure air
There is a large area at high altitude in China where it is necessary to build high voltage transmission lines and substations. Studying the discharge characteristics of several important types of electrical field is a very important topic in the development and building of power systems in a high altitude area. In this paper a series of tests have been done in a chamber, in which the air pressure could be changed. The tested models included sphere-sphere gap and point-plane gap. The discharges along dry clean, wet clean and wet polluted surfaces were also studied at different air pressures under both AC and DC voltages. The discharge characteristics of the above models at different pressure air were analysed and discussed.<<ETX>>