Research On DC Dielectric Properties Of XLPE Modified By Aromatic Derivatives

China has abundant offshore wind power,and for this type of new energy,the best transmission mode of the generated electricity is to employ flexible HVDC transmission.With the development of voltage source converter(VSC)and pulse width modulation(PWM)technology and the improved manufacturing level of DC cable,flexible HVDC transmission will become one of the most important ways for DC power grid.But the localization of XLPE insulation material required by flexible HVDC cable are still not achieved,which is very unfavorable for the development of Chinese wire and cable industry.Therefore,to develop crossing-linkable polyethylene insulation material with high performance for HVDC cable and strive to fill our gaps in HVDC cable insulation material has not only important scientific significance but also economic and social benefits,and will promote the holistic development of Chinese wire and cable industry.Four aromatic derivatives with different polar groups or molecular chains are elected on the basis of preliminary studies.XLPE insulation materials modified by aromatic derivatives are prepared by melt blending method.The DC dielectric properties of modified XLPE,the effect of temperature on the DC dielectric properties of modified XLPE,the emigration characteristic of the aromatic derivatives and the impacts of additives on the cross-linking reaction are mainly researched.The results show that the introduction of aromatic derivatives can increase the DC breakdown strength of LDPE and XLPE,improve the conductivity characteristics of XLPE and inhibit the accumulation of internal space charge;temperature is one of the important factors that influence the dielectric properties of the material modified by organics;aromatic derivatives have different degrees of impacts on mechanical properties,gel content,thermal elongation of XLPE and the crosslinking reaction of PE.