Research On The Suppression Method Of Space Charge In High Voltage Direct Current Plastic Insulated Cables

Direct current transmission technology has been a hot topic in the electrical engineering domain, on account of the considerably numerous advantages of it. The high voltage direct current plastic insulated cable is one of the most important equipments in DC transmission technology. Compared with paper insulated DC cables, there are many excellent characteristics of the HVDC plastic insulated cable, such as, relatively small volume, great transmission capability and maintenance-free. So it is crucial to research and develop HVDC plastic insulated cables. The non-homogenous distribution of space charge in the cable insulation may distort the distribution of electric field which will reduce the dielectric strength and accelerate the deterioration of the insulation. As a result, solving the problem of the space charge accumulation in dielectrics is the indispensable and first step to develop HVDC plastic insulated cables.The pulsed electro-acoustic method is utilized to investigate the space charge distribution in polyethylene and its composites and some conclusions can be drawn. The differences of production process among different types of polyethylene result in the differences of space charge distribution in them. Although loading with the same kind of filler and the same quantity and the base material is LDPE, LDPE produced by different corporation may also make each composite have different characteristics. The crystallization behavior of composites may also affect the space charge distribution in them. However, this affection is less effective than those of other factors, such as, the concentration of impurities. The cross-linking by-products impose great effect on space charge distribution in XLPE. The research results also show that the material of electrodes is also one of important factors which affect the space charge distribution.Loading proper quantity of nano-MgO can effectively improve the space charge distribution, the breakdown characteristics, conductivity and mechanical performances of composites. By utilizing FT-IR and DSC to investigate XLPE and MgO/XLPE nanocomposites, it can be inferred that there are some strong interaction between the molecular groups of XLPE and MgO nano-particles from analyzing the experiment results.