| The safety of power equipment is the first defense system of power grid security.Power transformer is the pivotal equipment of power system,and its operation condition has a direct impact on the safety and stability of the power grid.Therefore,it is of great significance to accurately assess the aging state of transformer oil-paper insulation and to ensure the normal operation of the power grid.Frequency domain dielectric spectroscopy(FDS)is a non-destructive diagnosis of frequency domain method,very suitable for transformer oil paper insulation state diagnostic field,especially in the low frequency and low frequency under the parameters of the measurement more accurately reflect the medium interface polarization and space charge polarization relaxation characteristics,reflect the actual development condition of the high voltage power equipment insulation aging.This paper first introduces the research status of the dielectric response method to diagnose transformer oil-paper insulation and the main problems in this method.The research object of this article for frequency domain dielectric spectroscopy,due to the frequency domain dielectric spectroscopy in low frequency band measurement need a very long time,and vulnerable to environmental factors,this paper provides a kind of based on parameter identification of equivalent circuit and estimate the paper insulation system low frequency dielectric loss method.Equivalent circuit model parameters and the frequency domain characteristics of transformation formula,using the data from the measurement of high frequency band by the optimization algorithm to identify the equivalent circuit parameters,the values of the parameters is obtained using identification into transformation formula,calculate the frequency domain to low frequency dielectric spectrum.This method because only need to measure the frequency of high frequency domain dielectric spectrum characteristics,and avoid the measurement of low frequency band,effectively reduce the time of field measurement,quickly and efficiently the research state of transformer insulation.In order to analyze the experimental results in theory,this paper studies the dielectric spectral characteristics of low frequency band in low frequency band based on the x-y model.In order to get the better promotion of the method,select different mathematical optimization algorithm,particle swarm optimization algorithm,leapfrog algorithm,the equivalent circuit parameters are identified,will be calculated by the different optimization algorithm to identify the error of the frequency domain to low frequency dielectric spectrum analysis comparison research.Results show that the identified based on the equivalent circuit of low frequency characteristic curve of two estimated values and the measured values coincide well,and the errors are within the scope of the permit,but overall the leapfrog algorithm identify with low error,which proved that the use of high frequency data,based on x-y equivalent circuit model to predict effective feasibility of frequency domain low frequency dielectric spectrum method and find out the optimal algorithm of this method is suitable for to leapfrog algorithm. |
