Research on Insulation Reliability of Submarine Cable Accessories for HVDC Transmission Applications

With its advantages of fast power regulation speed, high operating stability, no increase in system short circuit capacity and low line loss, HVDC transmission system has been widely used in long distance and large capacity transmission, asynchronous networking and submarine cables. With the addition of new energy sources such as offshore wind power, the application of submarine DC cable in power transmission have been widely applied recently. However, the accumulation of space charge and the difference of the conductivity of composite insulation in DC cable accessories often make the electric field distribution not uniform, resulting in electric field distortion, even breakdown. Therefore, it is necessary to improve the reliability and stability of the insulation of DC cable accessories. In this paper, a new type of accessory insulation material, the TiO
2
/1iquid silicone rubber nanocomposites with different concentrations were developed. The results show that the 4wt% TiO
2
/LSR nanocomposites has a good nonlinear conductivity characteristic, with the increase of electric field strength, it can maintain the same order of magnitude change with the conductivity of XLPE, achieving a good insulation match. And the PEA test show that the accumulation of space charge in the all TiO
2
/LSR nanocomposites samples is reduced compared with that in pure LSR sample. The 4wt% TiO
2
/LSR nanocomposites sample had the least amount of space charge accumulated, indicating that it can significantly inhibit the accumulation of space charge. It is realized to reduce the conductivity difference of cable composite insulation and suppress the interface space charge accumulation, promote the uniform distribution of the electric field in the cable accessories, and improve the reliability and stability of the insulation of the cable accessories.