The experimental investigation on space charge distribution of cellulose insulation paper modified with alumina nanoparticles

Convert transformer constitutes one of the most critical and strategic components in high voltage DC transmission line. The condition of insulation system in convert transformer directly affects the security and stability of the power grid operation. Cellulose paper as the main part of oil-paper insulation system is adversely affected by space charge under DC voltage. Depending on the injection and dissipation rate as well as the distribution of space charges, the internal electric field is distorted, which in turn leads to catastrophic failure of the insulation system, causing discontinuity in power system operation and great economic loss. Considering the irreversibility of the degraded cellulose paper, the original performance of cellulose paper is particularly essential. Studies has shown that the addition of nanoparticles into other dielectrics has been demonstrated to improve electrical performance, while the cellulose paper reinforced with nanoparticles are rarely reported. This paper aims at researching the influences on space charge distribution through using alumina nanoparticles to reinforce ordinary cellulose insulation paper. Samples with various Nano-Al
₂
O
₃
concentration were fabricated and pretreated first. The experimental results show that adding nanoparticles can inhibit the injection, migration and accumulation of space charge in dielectric, making the space charge distribution more uniform in insulation paper.