Design Method of Changing Medium Voltage Alternating-Current Cable to Direct-Current Operation

Abstract

Changing the existing medium voltage alternating current cable to transmit direct current is a feasible technical transformation scheme, which has obvious advantages in cable capacity increase and operation reliability improvement. At present, there is only one project case introduced in the alternating current to direct current conversion of medium voltage alternating current cables. Most of the studies are carried out from the perspective of theoretical analysis and design calculation. The research focuses on the constraints of alternating current to direct current conversion of different cables and the design of ampacity and voltage. This paper studies the design method of converting the existing alternating current cable to direct current, analyses some problems in the current design and the technical details that need to be further improved, and discusses the constraints of converting the medium voltage alternating current cable to direct current from the aspects of current carrying capacity design, system design and system design, insulation temperature difference and electric field inversion, voltage design, space charge accumulation threshold calculation, electrical type test, etc. On this basis, this paper puts forward a design idea of alternating current to direct current transformation of medium voltage alternating current cable based on comprehensive constraints and suitable for practical engineering transformation and makes an example calculation. Finally, it gives implementation suggestions for the electrical type test of alternating current to direct current transformation of medium voltage alternating current cable.