Calculation Of Breakdown Voltage Of Typical Air Gap Based On CS-SVR Model

The breakdown voltage of the long air gap is an important basis for the external insulation design of UHV transmission and transformation projects.The electrode structure,voltage waveform,meteorological conditions and other factors affect the breakdown voltage of the air gap,and the influence of each factor on the breakdown voltage of the air gap is more complicated,and there is a complicated coupling relationship.At present,the external insulation design of power transmission and transformation projects is mainly completed through the discharge characteristic test of the engineering real gap.It is not yet possible to use a complete physical model to obtain the breakdown voltage,and the use of conventional empirical formulas has strong limitations and large errors.Machine learning algorithms have unique advantages in dealing with multi-dimensional nonlinear relationships.Therefore,in order to solve the above problems,this thesis proposes a calculation method of air gap breakdown voltage based on the cuckoo search algorithm(CS)optimization support vector regression(SVR)algorithm model.Based on the switching impulse test data of rod-plane and rod-rod gaps,the influence of gap distance,air temperature,humidity and air pressure on U50%of rod-plane and rod-rod air gap is analyzed by using grey correlation algorithm,and the correlation degree order of each influencing factor and U50%is obtained.Based on the calculation results of the correlation degree,the calculation results of the rod-rod gap correlation degree and the rod-plane gap correlation degree calculation results are compared and analyzed,witch is concluded that the switching impulse discharge voltage dispersion of the rod-rod gap is higher than that of the rod-plane gap.Based on the CS-SVR model,the gap distance,air temperature,humidity and air pressure are taken as the input of the calculation model,and U50%is taken as the output.The model is used to predict the selected prediction data,and the prediction results are basically consistent with the experimental results,and the effect is better than the meteorological correction results;the U50%of rod-plane and rod-rod gap under extreme temperature and humidity conditions is calculated by using the model,and the calculation results are in line with the reality.It provides a new idea for obtaining the breakdown voltage of the air gap under different meteorological conditions.Based on the CS-SVR model,a prediction model of U50%switching impulse of tower gap is established by using the experimental data of rod-plane gap and part of tower gap switching impulse discharge.The model takes the characteristic quantity of electric field nonuniformity,gap distance and meteorological conditions as input,and the U50%switching impulse of tower gap as output.The ±1100kV tower gap switching impulse discharge test was carried out,and 10 groups of tower gap discharge test data were obtained as the validation group to verify the effectiveness of the model,which proved the effectiveness of the tower gap prediction model.It has certain guiding significance for obtaining engineering air gap discharge characteristics.