温度梯度下动态交联复合树脂的高温工频沿面闪络特性OA

During the development of high-voltage electrical equipment to high-voltage,large-capacity,and compact,conductor heating can easily cause serious distortion of the electric field at the metal/gas/solid three-nodes of the insulator,induce surface flashover faults,and seriously threaten the stable operation of the power system.Due to the complex preparation process,high cost,many interface defects and poor high temperature stability,traditional functionally graded materials(FGM)are difficult to adapt to the electric field regulation requirements in different field strength regions,and the improvement of surface insulation performance is limited.In order to solve this problem,this paper proposes an electric field control method using temperature gradient to induce dielectric gradient in situ,which provides a new path for high temperature power frequency flashover suppression of high voltage equipment. The dynamic cross-linked composite resin systems with different dynamic ester bond contents were constructed,including pure resin(E51),interpenetrating network resin(IPN1,IPN2)and micro/nano composite resin(IPN-nS/BN).The properties of the materials were characterized by dynamic thermomechanical analysis,stress relaxation test and dielectric property test.The correlation mechanism between temperature gradient,dielectric gradient and electric field distribution was explored by combining the power frequency surface flashover experiment and electro-thermal coupling finite element simulation under temperature gradient. The results show that the surface temperature gradient of dynamic cross-linked resin can induce the dielectric gradient in situ,and the higher the content of dynamic ester bond,the more significant the dielectric gradient effect.The IPN2 resin has the most prominent dielectric gradient due to its rich dynamic ester bonds.The maximum electric field strength on the surface of IPN2 resin is 26%lower than that of ordinary E51 resin,and the power frequency surface flashover voltage at 100℃is 11.7%higher than that at room temperature.When the temperature exceeds 100℃,the surface flashover voltage of all resins decreases sharply,and the flashover voltage of the dynamically cross-linked resin is more sensitive to temperature changes.Although the micro/nano composite resin has higher thermal conductivity and more uniform surface temperature distribution,the dielectric gradient effect is weak,and the flashover voltage improvement effect is not as good as that of the interpenetrating network resin.The dielectric properties test showed that the dielectric constant of the dynamic cross-linked resin increased exponentially with the increase of temperature.Under low frequency conditions,the increase of dielectric constant was significantly higher than that of ordinary resin due to the interfacial charge accumulation effect,which was the core mechanism of its dielectric gradient control ability. The dynamic cross-linked resin system does not require complex preparation process,and the dielectric gradient is formed by temperature gradient self-induction to optimize the electric field distribution,which reduces the preparation cost and improves the adaptability of electric field regulation.The electric field regulation mechanism of dynamic cross-linked epoxy resin to suppress surface flashover under temperature gradient revealed in this paper provides theoretical basis and technical support for the optimal design of insulation materials for high-voltage electrical equipment,which is of great significance to promote the development of high-voltage equipment towards miniaturization and high reliability.