Measurement And Modeling Methods For Broadband Characteristics Of Large-Scale Electrical Equipment

With the development of "double high" power system,a variety of broadband oscillation problems appear in power system,so it is urgent to obtain the broadband model of corresponding equipment.In order to build the broadband model of electrical equipment,it is necessary to measure the broadband impedance characteristics of the equipment.However,the large size of high voltage electrical equipment requires a long measurement lead to measure the broadband impedance characteristics.At present,there is a lack of effective and universal compensation measures,which will lead to unacceptable measurement errors in the high frequency range.Therefore,how to accurately measure the broadband impedance characteristics of electrical equipment is very important,which lays a foundation for the after-demand broadband modeling and prediction analysis of various broadband problems.In order to solve these problems,this paper proposes a long lead measurement and verification method for wide-band impedance characteristics of large-scale electrical equipment,which solves the problem of too long shield lead line in wide-band measurement.A modeling scheme for broadband measurement of key equipment in converter station is presented to solve the problem of low frequency oscillation in broadband measurement.Based on the measurement modeling method proposed in this paper,the broadband models of a series of key equipment in UHV converter station are established.Firstly,the long lead modeling method based on PEEC is analyzed in detail,and the coupling calculation model of the long lead above the earth is established.The"integrated" coupling verification model of coaxial cable is obtained.The model can consider the influence of the shielding layer’s leading line well,and the correctness of the program is proved by simulation analysis.The effectiveness of the modeling method is proved by measurement experiments in laboratory.Secondly,the measurement and verification method of long lead of large scale electrical equipment is studied and analyzed.Impedance analyzer 4294A is used as the measuring equipment,and the measurement and verification method based on PEEC is proposed.The method calculates the network parameters of long lead and shield lead through PEEC,and uses the network parameter matrix to eliminate the lead parameters.A measurement calibration method based on PEEC local modeling is proposed.The network parameters of this method are obtained from the open circuit,short circuit and load data measured by PEEC and impedance analyzer.Finally,according to the two measurement calibration methods,the accuracy of the measurement calibration method is proved by experiments.Finally,the measurement and modeling of key equipment in converter station are studied.A modeling scheme of integrated broadband model is proposed,and the measurement results are optimized by genetic algorithm.The ground measurement scheme of impedance analyzer is improved,and the accuracy of measurement data can be guaranteed by using the measuring loop with the H end of impedance analyzer grounded and the shielding layer shorted.Based on the method proposed in this paper,the broadband models of flat-wave reactor,resistance-capacitance divider and cascade flat-wave reactor in UHV converter station are established.