Research On Measurement And Modeling Methods Of Broadband Characteristics Of Electrical Equipment

The black box modeling method is a better choice when the detailed int ernal structure of the equipment is unknown.This modeling method requires accurate swept-frequency measurements of the admittance or impedance parameters of the ports.In some cases,longer test leads are required due to the larger size of the electrical equipment under test.This causes unacceptable measurement errors at high frequencies.Aiming at the problem of broadband measurement and broadband modeling of electrical equipment under long test leads,this paper studies the measurement method of broadband characteristics of electrical equipment ports by combining theoretical calculation and experimental measurement.The broadband equivalent circuit models of transformers and reactors are established a nd the validity of the models is verified.In this paper,the measurement principle of the impedance analyzer is firstly studied,and the characterization method of the port transfer impedance measured by the impedance analyzer is obtained by deduction.On this basis,the factors affecting the measurement accuracy are simulated and analyzed.As well as the non-ideal characteristics of the compensation terminals will have a certain impact on the measurement results and may even cause passive violations.On the basis of the above analysis,this paper discusses the normative wiring method for the measurement of large-scale electrical equipment.The different values of lead segment lengths under the two basic wiring methods are simulated and analyzed,and the segment lead length configurations with the s mallest error are obtained respectively.This paper proposes a novel compensation method for measuring the broadband impedance of large-scale electrical equipment.This method converts nonlinear problems into linear problems to obtain a unique solution,which can effectively eliminate the transmission line effect of long test leads and the connection between open/shorted/50Ω load compensation terminal.The method is theoretically verified by the method,and the results show that the method is effective.This method is experimentally verified by so me tests on components with different characteristics using 30 m long test leads in the 40Hz～10MHz frequency band.The results show that compared with the traditional open/short/load compensation method,the new compensation method has higher accuracy.In this paper,the reactor is used as the single-port network modeling object,and the transformer is used as the two-port network modeling object.The broadband characteristics of its ports are measured respectively,and the broadband modeling is carried out by the vector matching fitting method and the multi-port Brune network synthesis method,and the corresponding broadband equivalent circuit model is obtained.The accuracy and validity of the established model are verified by comparing the simulation of the voltage s urge waveform in the time domain of the transformer model with the actual measurement results.