Numerical Calculation And Global Optimization On Electric Field Intensity Of Ultra-high Voltage

The ultra-high voltage (UHV) transformer is one of the most important equipment in transformer substation. The insulation design is significant for the capacity limit and the function reliability of UHV transformer. It is necessary in the UHV transformer insulation design to analyze the electric field and decrease the electric field strength around the oil gap. The electric field strength and uniformity of transformer coil and outlet device have direct influence on the qualification and economic indicator as well as economical efficiency and stabilization of the UHV transformer. Thus, it is significant to carry out the numerical calculation and optimization on the electric field of the UHV transformer coil and outlet device.In this paper, the 3-D solid model is built for an UHV transformer prototype. 2-D electric field of the model middle part is calculated for preliminary confirmation of the critical area which needed selective calculation. The analysis method is employed to solve the equivalent dielectric constant considering the multilayer insulation oil-paper as homogeneous medium, and then the 3-D solid model can be simplified by dividing the model into two parts, the upper half and the lower one. The 3-D finite element meshing model is constructed by manual and auto-meshing generation so as to calculate the electric field around the upper half coil and the lower one, respectively. Voltage and electric field distribution are obtained, and the maximum electric field strength is calculated as well as its location is found. These calculated results verify the reasonability of the insulation design of the prototype's coil and outlet device. To improve the coil and outlet device design efficiency, the finite element analysis is employed instead of fast and efficient parametric method of common model. The parametric finite element analysis file for electric field of coil and outlet device is compiled by APDL. And the variable parametric finite element calculation is established by invoking ANSYS in the computer programming to realize automatically processing batch. Furthermore, the maximum electric field is optimized by zero order optimization method in upper and lower model, and the optimal solution can be obtained. The overall optimized solution is obtained by comparing the optimized solutions of upper and lower model.The interface programming between ANSYS and other outer computer code is discussed in this paper, and the interface program code is proposed to link VC++6.0 and ANSYS. ANSYS can be invoked as VC++6.0's subroutine by this interface program. Then the genetic algorithms and the finite element analysis are integrated to optimize the electric field of UHV transformer coil and outlet device by operating parameter delivery in VC++6.0 and ANSYS programming. Finally, particle swarm algorithm is introduced to optimize the electric field of the UHV transformer coil and outlet device with the same method. Additionally, merits and demerits are analyzed on the optimization algorithms of this paper.