Fast Calculation For Scattering Characteristic Of UHV Power Line Based On Model-based Parameter Estimation Technique

Along with the rapid developing technology, there comes various electronic products and light-current system with increasingly high demands for the surrounding electromagnetic(EM) environment. Thus, the reradiation interference(RRI) to the adjacent wireless electronic facilities from UHV power line are more serious. In the research of RRI, the scattering fields of power line on wide frequency band are often calculated by swept-frequency method. Nevertheless, the various frequency-domain algorithms, e.g. method of moments(MoM) and uniform theory of diffraction(UTD) can only calculate one frequency point, the huge calculation demand in RRI research can’t be solved under the existing computer hardware. Therefore, considering to introduce a new theory, an efficient and fast calcultaion method for the high-frequecy and broadband scattering characteristic of UHV power line has become a primary task in the research field of RRI.In this paper, instead of the traditional frequency-domain algorithms, the MBPE (Model-based Parameter Estimation) technique was proposed to deal with this problem. Firstly, the scattering field information of sampling points were calculated with MoM, therefore, the scattering characteristic of power line could be acquired by interpolation fitting.The main contents are as follows:1) Based on the generalized resonance theory, the EM lossy open system in the wide space consisted of power line and antenna could be established. The complex power equations for both EM open system and closed system were deduced. The corresponding function relation of the complex power energy in the two systems was constructed. Considering the balance relation of complex power energy, the EM lossy open system consisted of antenna and power line could be equivalent to a generalized closed system.2) The fast solution thinking of impulse response in EM closed system was introduced. Based on the MBPE technique, the generalized system function for the equivalent scattering closed system was deduced. The Pade rational function was selected to interpolate the variation of scattering field. The scattering fields of sampling points with equally spaced frequency were respectively calculated. Therefore, the scattering field frequency response of power line could be quickly obtained.3) Take the frequency band studied by IEEE and the operating frequency band of AM broadcast radio stations for examples, the scattering fields of sampling points with equally spaced frequency were respectively calculated corresponding to the wire model of500kV double-circuit power line and the wire-surface model of±800kV Xiangjiaba-Shanghai UHVDC power line. The generalized system functions were established to interpolate the variation of scattering field. As a result, the values of scattering fields on frequency bands of two examples could be quickly calculated. The research showed that, the calculation amount of MBPE technique is reduced to1/5compared to the traditional frequency-domain algorithms, and the fitting accuracy of MBPE technique was correlated with the numbers and locations of sampling points, and the maximum relative error for extreme points could be under4.0%with appropriate sampling points using the windowed interpolation MBPE technique.4) China Three Gorges University, North China Electric Power University, China Electric Power Research Institute(Wuhan) and China Ship Research and Design Center organized and carried out the single and multi-base1000kV cat-head tower scaled model experiment with1:30size ratio in10m anechoic chamber and open field respectively. Comparative analysis of interpolation results and experimental data found that the global mean absolute error and the global maximum relative error for extreme points were0.00271V/m and4.3%.