Abstract
Cellulose polymer insulation material is widely used in oil immersed bushing. Moisture is one of the important reasons for the deterioration of cellulose polymer insulation, which seriously threatens the safe and stable operation of bushing. It is significant to study the polarization and depolarization behavior of oil-immersed cellulose polymer insulation with different moisture condition under higher voltage. Based on polarization/depolarization current method and charge difference method, the polarization/depolarization current, interfacial polarization current and electrical conductivity of cellulose polymer under different DC voltages and humidity were obtained. Based on molecular-dynamics simulation, the effect of moisture on cellulose polymer insulation was analyzed. The results show that the polarization and depolarization currents become larger with the increase in DC voltage and moisture. The higher applied voltage will accelerate the charge carrier motion. The ionization of water molecules will produce more charge carriers. Thus, high DC voltage and moisture content will increase the interface polarization current. Increased moisture content results in more charge carriers ionized by water molecules. In addition, the invasion of moisture will reduce the band width of cellulose polymer and enhance its electrostatic potential, so as to improve its overall electrical conductivity. This paper provides a reference for analyzing the polarization characteristics of charge carriers in cellulose polymer insulation.
Highlights
The oil-immersed transformer is the core equipment of power transmission in the power grid, wherein safety and stability are significantly important to energy security and social stability
Wenyue Ye, et al found that the structure of liquid-solid interface is determined by the interaction between insulating oil and cellulose polymer paper, which is based on the Van der Waals effect, and water molecules will gather at the interface because of the interaction of the liquid-solid interface at certain electric field value [4]
Haoxiang Zhao et al found that when charge carriers pass through the interface between cellulose polymer paper and oil, the insulating paper has an obstruction effect, while the existence of water molecules would produce more charge carriers and reduce the obstruction effect, resulting in lower conductivity of cellulose polymer paper and different dielectric response characteristics [6]
Summary
The oil-immersed transformer is the core equipment of power transmission in the power grid, wherein safety and stability are significantly important to energy security and social stability. While PDC is used to analyze the charge accumulation and charge carrier relaxation behavior of cellulose polymer paper because it can measure the time domain dielectric response characteristics of insulating oil and cellulose polymer paper. Some scholars have studied the correlation between the dielectric characteristic parameters of casing insulating paper in time domain and moisture, most of the research is based on low excitation voltage, resulting in low signal-to-noise ratio, which is easy to be interfered with by environmental noise. This paper studies the time domain relaxation behavior of charge carriers for cellulose polymer insulation used in oil immersed bushing under higher voltage. Polarization/Depolarization Principle and Charge Analysis for Composite Polymer Medium By applying and removing DC voltages to the insulating medium, the dielectric orfe sponse characteristics in time domain from the polarization and depolarization current can be extracted based on a PDC test. SSiinnccee tthheeeelleeccttrriiccaallccoonndduuccttiivviittyyooffaalulummininuummfofoililisismmuuchchggreraetaetrerthtahnanthtahtaot foifnisnuslua-tliaotniooniloailnadndthtehtehtihcikcnkensesssofoaf laulmumininuummfofoililisisnneegglilgigibibleleccoommppaarreeddwwitithhtthhaattooffcceelllluulloossee ppoollyymmeerrininssuulalatitoionn, ,wwhihcihchmmeaenasnXs eXqueqalusatlos 1t,oth1e, tehleecterlieccatlrcicoanldcuocntidvuitcytiovfitcyelolufloceselluploolsyempoelryimnseurlaintisounlactaionnbceasnimbpelsifiimedp,liafnieddt,haenedletchterieclaelcctorincdaluccotinvdituycotifvtihtye coeflltuhleosceelpluolloysme eproilsaysmsehroiws nasinshEoqwunatiinonE(q1u2a).tion (12)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
