Optimum Design And Realization Of 96kVA High Voltage Medium Frequency Transformer

With the rapid industrialization in China, the control of dust pollution in coal combustion has become an important issue in environmental protection. Compared to other dust removal technology, the electrostatic precipitator (ESP) has the advantages of strong controllability, low energy consumption and high efficiency. Specially, the medium frequency (MF) ESP could reach relatively high power level and safety at the same time, and it could also be upgraded from the line frequency equipment with low cost. Thus it is the ideal option for the ESP application. The MF transformer serves as a connection of the power cabinet and dust collector, which makes it the key component of the whole ESP system. The main task of this work is to find the optimal design for high power MF transformer in ESP application.Firstly, the basic principle along with the difficulties in the design and manufacture process of MF power transformer is introduced. The multi-physical model of MF power transformer is given, the reluctance of mouth-shaped core is calculated, the calculation method of parasitic capacitance of transformer is introduced, different core losses calculation methods are analyzed and compared, and finally, the analytical calculation method of the temperature rise is introduced.As one of the highlights in this work, the medium/high-frequency effects of the conductors in transformer are detailed analyzed. Different types of ac resistance and inductance calculation methods are introduced and compared, the equivalence principle of area is given. The major reason for the errors of ac resistance calculation formulas and the related parameters are analyzed. The proper ac resistance calculation methods are carefully selected with the help of finite element simulation and low power prototype measurement results. The optimum conductor diameter calculation method by Professor Hurley is detailed introduced, several factors which contribute the error of this method are analyzed. With the controlling variable method, different kinds of winding arrangements are compared. Based on the conductor arrangement comparisons, the optimum winding design method for both inductor and transformer is proposed, the mathematical model is derived and verified.Finally, based on the theoretical model, the simulation and experiments are further implemented. Various transformer design constraints are introduced. The double 2D finite element simulation method for the EE core is introduced, and also successfully applied in the mouth-shaped core simulation, both the accuracy and efficiency of the simulation are improved. The MF power transformer design process is deeply optimized. The double 2D finite element simulation method is integrated into the design flow to improve the efficiency of the design process. The optimization of the design is based on the minimum slover within the design constraints. Several MF high power transformer prototypes are built and the related parameters is extracted and compared by analytical formulas, finite element model and experimental tests, which verifies the feasibility and accuracy of the design scheme.