Measurement And Calculation Of Wide Band Network Parameters Of10kV Single-phase Two-winding Transformer

The suppression and protection of over-voltage in power systems, as well as the research of electromagnetic compatibility in power systems need to build electromagnetic transient model of the components and equipments.The transformer model in the Electromagnetic Transient Program (EMTP) can only be used to the steady-state and transients calculation in50Hz and low frequency (≤10kHz). Because of the lightning impulse voltage and VFTO caused by the switching operations in gas insulated substation made the calculation upper frequency extended in MHz and a few tens of MHz, conventional transformer device circuit model obviously can’t meet the requirement of simulation, therefore, it is necessary to establish their high-frequency circuit model.The establishment of the Macro-model for the transformers is based on its network parameters. But the measurement of the wide band network parameter of the large-scale transformers is full of difficulties. Based on the National Natural Science Foundation project, Research of the Establishment of the Passive Wide Band Macro-model of Transformer Device (No.50977301), in order to overcome this problem, the paper adopts the finite element method to calculate the wide band admittance parameter of10kV single-phase two-winding transformer.First, the wide band network parameters of a10kV single-phase two-winding transformer is measured using impedance parameter measurement method, scattering parameter measurement method and impulse response method, then it is converted into the voltage transfer function. Through comparison and analysis on the measurement results, which can verify the validity of the measuement method.Second, establishing the multi-conductor transmission lines model of the lOkV transformer winding according to its actural structure, then adopt the finite element method to calculate its capacitance parameter, inductance parameter, resistance parameter and conductance parameter. Then using the telegraph equation of multi-conductor transmission lines model and the boundary conditions, we can derive the wide band admittance parameter of the10kV transformer.At last, to verify the validity with the method of calculation, converting the scattering parameter of the10kV transformer into its admittance parameter. The comparison of calculation results and measurement results verify the feasibility and effectiveness of the demonstrated method.