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Leakage current that is strongly relative to the contamination flashover of outdoor insulators easily monitors online. In the paper, a BP Artificial Neural Network (ANN) model is proposed to predict the equivalent salt deposit density (ESDD) value based on the leakage current characteristics and environmental parameters which are both from artificial pollution tests. The contamination degree of insulators online monitoring is realized by using the proposed model. The data reflecting the relationship between the ESDD and the time is obtained from the natural contamination tests, and then the other ESDD prediction model is established based on the non- linear time series through analyzing ESDD time series properties. The second proposed model has high prediction precision, but in practical engineering, the data of ESDD can be obtained is very limited and need to be measured under a power outage condition. In order to get the better precision and practicality of the prediction, a new combination forecasting model is built, which the ESDD nonlinear time series prediction model is a correction model for the ANN model. The combination forecasting model is verified by part of experimental data, and the results show that higher precise online monitoring of contamination degree of insulators is achieved, the error is within ±4.3% and the prediction precision is 54% higher than that of the ANN model.

A novel risk forecasting model of high voltage circuit breaker insulation based on double artificial neural networks is proposed in the paper by analysis of the relationship between ESDD, flashover voltage and environmental factors. The data used to build the forecasting model is obtained from artificial pollution test. The proposed insulation fault risk forecasting model calculates the insulation fault probability under given environmental factors. Results of artificial pollution text indicate that the forecasting of this method is satisfied to practical application and useful to theoretical research.

To improve the accuracy and speed of fault current computation, a variable step size window length adaptive algorithm based on the adaptive filtering theory is proposed in the paper. Digital signal processing algorithm is one of the most important factor for the current protection algorithm. The paper analyzes the principle of the proposed algorithm and the way how to vary the step size and window length. The proposed adaptive algorithm can change the step size of the length changeable window in the filtering algorithm. It is sensitive to fault signals and has a fast response speed, and also have a more efficiently performance. The results of simulations show that the algorithm possesses good performance and is suitable for realizing the fast current protection function to the intelligent high voltage circuit breaker. According to the definite criterions to choosing the fault line, both theoretical analysis and simulation results show that the method has satisfactory reliability and sensitivity.

In order to study the effect of pollution un-uniform distribution on insulation performance of outdoor insulators, in the paper, the size of the dirt layer conductivity is used to describe the pollution extent of insulators and then the three-dimension harmonic quasi-static electric field of XP-160 insulators under pollution un-uniform distribution is calculated. The effects of different conductivity of dirt layers and several typical pollution un-uniform distributions to the electric field distribution along the surface of insulators are investigated. Comparing the leakage current obtained from artificial contamination test with the results of calculation, the reliability of the model is verified.

The structure and parameters of the motor used in the operating mechanism is designed according to the characteristics requirement of disconnecting switch. The two kinds of stator winding structures, one of which is stator winding symmetric distribution and the other one of which is stator winding asymmetric distribution, are proposed in the motor design. The dynamic simulation is achieved by using the finite element method according to the two kinds of stator winding structures. The simulation results verify the reasonable of motor design and gain the characteristic curves (torque, current, revolution and angle, etc.). The analysis results indicate that both of the two stator winding structures motor have an excellent performance which can give a sufficient opening or closing speed to meet the requirements of disconnecting switch.