PROJECT TITLE :

Research on Overvoltage for XLPE Cable in a Modular Multilevel Converter HVDC Transmission System

ABSTRACT:

Thanks to the fast development of the voltage-source converter (VSC), the strain for HVDC cables have increased significantly. Although a lot of than ten VSC-HVDC projects are beneath construction and many a lot of are in operations globally, the testing criteria for HVDC XLPE cables are mainly referenced to check guideline TB 496 suggested by CIGRE. Due to the large stray capacitance of the VSC-HVDC cables, the switching impulse overvoltage stress of the cables is the most electrical parameter involved, a unified overvoltage factor of 2.one p.u. being typically accepted. However, the switching impulse overvoltage stress of a VSC-HVDC cable system depends on not solely the VSC topology but conjointly the cable parameters and also the volt-ampere characteristics of the dc cable surge arresters used. This paper studies the switching impulse overvoltage stresses for the dc cable system of a symmetrical monopole VSC-HVDC transmission system using the modular multilevel converter technology. The studies were performed consistent with the key technical parameters for a typical 1000-MW/320-kV VSC-HVDC transmission theme, the XLPE dc cable links being assumed. The results show that a switching impulse overvoltage level of 2.3 p.u. ought to be applied during the type test of the overvoltage capability of the HVDC cables.