Assessment Method Of Power Transformer Oil-paper Insulation Based On Dielectric Response Technology

The oil-impregnated transformer is the core equipment for energy delivery and distribution in the process of power grid safe operation.So,the security problem of transformer get more and more attention.How to evaluate the exact aging condition of transformer insulation and take fault diagnosis on it has important significance for the improvement of the reliability of power system.The principle of dielectric response has the advantage of non-destructive measurement,user-friendly control and strong anti-interference ability.Thus,it is used as the diagnostic tool for condition evaluation of oil-impregnated transformer by scholars at home and abroad.In this paper,First of all,dielectric response technology of oil-paper insulation in transformer is introduced.Then,Compared to the traditional transformer insulation test and traditional transformer main insulation moisture content test respectively.Lastly,this paper discusses the feasibility of the dielectric response technology,which is applied to scene to evaluate the transformer oil paper insulation condition.At First,the development status of dielectric response technology at domestic and international has been discussed.Second,the extended Debye model and X-Y model are introduced,the results of PDC and RV M measurement technology are connected by extended Debye model according to circuit principle analysis.Then,the main insulation state of transformer at the scene is evaluated by the dielectric response technology and traditional insulation test respectiv ely.At last,the dielectric response technology and traditional water content test method is used to contrast the difference of evaluating paper moisture content of the main insulation in transformer.The main achievements made in the paper are follows:(1)In addition to get the traditional insulation parameters,oil and paper conductivity can also be extracted by dielectric response technology.According to the two new transformers test results at the scene,it can be seen that the insulation state of two transformers are the same,which is exactly consistent with true state.The assessment results of main insulation moisture content show that the results of dielectric response technology is reasonable.(2)The measured dielectric response curve of two tr ansformer at the scene by dielectric response technology,Some part of traditional insulation parameters can be calculated by the measured dielectric Response curve.Due to the different voltage level and test principle,the results of the insulation param eters between dielectric response technology and traditional insulation test have some differences,but the difference of power frequency capacitance and dielectric loss factor is not big.Although the results of insulation resistance,absorption ratio and polarization index have some differences,we can consider that the parameters of the same transformer is used to analyze in the longitudinal comparisons by dielectric response.(3)The results of transformer main insulation content by dielectric response method is close to results of traditional content test by Oommen curve.Both of two methods can be effective to evaluate the content of transformer main insulation,and dielectric response technology can avoid the influence of human factors in the process of sampling,at the same time the insulation paper,which cannot be taken at the scene,is used to test directly,so as to reduce the measurement error.