Research On A Fractional Order Broadband Circuit Model Of The PT

Voltage transformer has an important role in the field of power system measurementand protection, its electromagnetic characteristics affect the power system performance.The transformer simulation model is an effective way to study the problem oftransformer core saturation. Traditional equivalent circuit model with simple structureand clear physical meaning has been used widely. At low-frequency condition, thetraditional equivalent circuit can achieve an accurate simulation of devices. However,with the growing demand of broadband modeling, the defect of traditional equivalentcircuit model becomes significant. The transformer core will very easily reach saturationdue to over-voltage.The magnetic flux density B and the magnetic field strength Hexhibit a hysteresis loop shape, showing a nonlinear relationship. In recent years,fractional calculus theory in the field of modeling and controling getting more attention,and it particularly suitable for describing the genetic characteristics of dynamic system.Fractional calculus can be effectively applied to simulate the dynamic characteristics ofdifferent materials.This paper presents a new digital potential transformer (PT) model. Due to theeffect of hysteresis and saturation phenomenon, the magnetization curve of iron core hasa strong nonlinear. From the perspective of hysteresis effect of iron core, this articlepresents a PT core model using the theory of fractional calculus, then using the scatteringparameter data to determine the resistance, inductance and stray capacitance. Finallyproposing a new PT broadband circuit model. The model simulates the nonlinear part ofiron core using the fractional order expressions and can reflect the feature of saturation.Finally it shows the correctness and validity of the model through the theoretical analysisand simulation results.