Study On Characterization Of Migration Behavior Of Organic Electric Field Regulator In LDPE

The increase of voltage level of power systems and the development of centralized and miniaturized power electronic devices make insulating materials or insulating structures often work under the condition of the uneven electric field.Working under uneven electric field for a long time will lead to deterioration and aging of insulation.Regulating the distribution of electric field inside insulation has become an important subject in the field of high voltage and insulation.The polymer containing a specific polar group is added to the LDPE matrix,so that the composite has field-enhanced nonlinear conductivity and polarizability.The conductivity of the composite is positively correlated with the content of the polar polymer,and the polar molecules migrate to the strong electric field region under the uneven electric field gradient force.The nonlinear dielectric properties and migration effect can be used to adaptively adjust the electric field distribution in composite,which are defined as organic electric field regulators.It is of great significance to characterize and verify the adaptive dynamic regulation of uneven electric field by the migration behavior of organic electric field regulators.To characterize the migration behavior of organic electric field regulator under the action of electric field gradient force.In this thesis,two organic electric field regulators,polyethylene glycol monomethyl ether(MPEG)and allyl polyethylene glycol(APEG),were selected as fillers.Firstly,the infrared spectroscopy test and the capacitance test of the composite under uneven electric field were carried out.Due to the limitation of the resolution and accuracy of the test equipment,the two methods could not effectively characterize the migration behavior of the organic electric field regulator.Considering that the space charge test can reflect the spatial information inside the dielectric,the space charge test of the composite material with different filler content was carried out.The test results show that the two fillers can effectively reduce the electric field distortion rate inside the composites,and the adaptive dynamic regulation of the electric field distortion rate inside the composite can be realized under specific content and temperature,but the migration behavior of the fillers cannot be intuitively characterized.The experimental conditions and types of fillers with obvious effect of dynamic electric field regulation were selected.Taking the relationship between the electrical conductivity of composite and electric field strength as well as filler content as a reference standard,a distributed equivalent circuit model was established by mean of PEA and polarization current time domain spectrum measurement to obtain the temporal and spatial evolution information of electric field intensity and conductivity in composites.Combining the above results,the spatio-temporal evolution information of the filler content can be obtained.The results show that the organic electric field regulator in the composites can migrate under the action of electric field gradient force and form a concentration gradient distribution for electric field regulation.It also indicates that the combined measurement technique based on PEA and polarization current time domain spectroscopy can be used as an effective means to verify and characterize the migration behavior of organic electric field regulators.