Synthesis of a Novel Semi-Conductive Composites Doping with La0.8Sr0.2MnO3 for Excellent Electric Performance for HVDC Cable

Abstract

The semi-conductive layer located between the wire core and the insulation layer in high voltage direct current (HVDC) cable plays a vital role in uniform electric field and affecting space charges behaviors. In this work, the research idea of adding ionic conductive particles to semi-conductive materials to improve the conductive network and reduce the energy of the moving charge inside it and to suppress charge injection was proposed. Semi-conductive composites doped with different La0.8Sr0.2MnO3 (LSM) contents were prepared. Resistivity at different temperatures was measured to investigate the positive temperature coefficient (PTC) effect. Pulse electro-acoustic (PEA) method and thermal-stimulation depolarization currents (TSDC) tests of the insulation layers were carried out. From the results, space charge distribution and TSDC currents in the insulation samples were analyzed to evaluate the inhibitory effect on space charge injection. When LSM content is 6 wt. %, the experimental results show that the PTC effect of the specimen and charge injection are both being suppressed significantly. The maximum resistivity of it is decreased by 53.3% and the insulation sample has the smallest charge amount, 1.85 × 10−7 C under 10 kV/mm—decreased by 40%, 3.6 × 10−7 C under 20 kV/mm—decreased by 45%, and 6.42 × 10−7 C under 30 kV/mm—decreased by 26%. When the LSM content reaches 10 wt. %, the suppression effect on the PTC effect and the charge injection are both weakened, owing to the agglomeration of the conductive particles inside the composites which leads to the interface electric field distortion and results in charge injection enhancement.

Investigation on effect of semiconducting screen on space charge behaviour of polypropylene‐based polymers for HVDC cables

“…Regarding fillers for constructing conductive networks, carbon black still dominates because of its high dispersibility, low cost, and high conductivity compared with other conductive fillers. The performance of carbon black reinforced semiconducting screens for HVDC cable is controlled by multiple factors, including carbon black type, purity, filler size, concentration, and dispersion state [10,13,[17][18][19]. It is widely believed that uniform dispersion of carbon black with high purity and small particle size leads to high electrical conductivity, less space charge accumulation in the insulation interface, and durable mechanical properties.…”

Charge Injection and Dielectric Characteristics of Polyethylene Terephthalate Based on Semiconductor Electrodes

“…The composition of copolymer determines its compatibility with CB, which leads to considerable discrepancy in the aggregation morphology and dispersivity of CB in semi-conductive polymeric composites, and thus affects charge injections at the interface between semi-conductive shielding and insulation layers [ 18 , 19 ]. By introducing fast-ionic conductors into semi-conductive composites, a favorable conductive network could be established to increase the positive temperature coefficient and reduce the kinetic energy of transporting charges, thus improving space charge characteristics of insulation layer [ 20 , 21 ]. Due to the difference of material structures between the composite semiconductor and insulating polymer that should be developed for cable fabrications, pertinent technologies of polymeric hetero-junctions and surface electrodes are urgently desired for constructing the insulation system of transmission cable.…”

Influence of the Semiconductive Composites Doped with Li4Ti5O12 on Space Charge Implantation in LDPE

“…Usually, a semiconductive screen consists of two layers in a single core HVDC cables: an inner layer sandwiched between the copper conductor and the insulating layer and an outer layer sandwiched between the insulating layer and the wire metallic shield. Furthermore, doping a screen material with ionic conductors such as La 0.8 Sr 0.2 MnO 3 , La 0.6 Sr 0.4 CoO 3 , or SrFe 12 O 19 magnetic particles represents an effective way of enhancing the conductive network and inhibiting space charge implantation [18][19][20]. A typical semiconductive screen is fabricated from a composite material consisting of a polymeric matrix, low-density polyethylene (LDPE), ethylene-vinyl acetate copolymer (EVA), and carbon black (CB) particles [21][22][23][24], which are dispersed across the matrix to form a conductive network.…”