Optimal Content Selection of Voltage Stabilizers Using TOPSIS Method to Achieve Enhanced Material Properties for HVDC Cable Insulation Applications

Three different contents (1, 3, and 5 wt%) of 4-n-propylbenzoic acid as the voltage stabilizer are added to cross-linked polyethylene (XLPE), whereas electrical, mechanical, and thermal properties of XLPE/stabilizer blends are measured. The obtained results show that the voltage stabilizer addition facilitates a reduction in accumulated space charges and conduction current and improves the life exponent and thermal conductivity of the XLPE but negatively affects the degree of cross-linking. The optimal content of the voltage stabilizer to attain the balanced overall properties is selected by the technique for order of preference by similarity to ideal solution (TOPSIS) method. The electric field distortion rate, conduction current, and temperature sensitivity of electrical conductivity under 40 kV/mm, dc breakdown strength, thermal conductivity, gel content, elongation at break, tensile strength, crystallinity, and temperature at a maximum decomposition rate of the samples are selected as evaluation indices for the TOPSIS method, which yields the 1 wt% of 4-n-propylbenzoic acid as the optimal content. The calculated life exponent is maximum for the XLPE-1, suggesting that the high voltage direct current (HVDC) cable having XLPE insulation with the optimal content of the voltage stabilizer will have a longer service life.