Effects of Current Limiting Characteristics of Resistive Type Superconducting Fault Current Limiter on Flexible DC Transmission System of Offshore Oil Production Platform

Abstract

Voltage Sourced Converter based High Voltage Direct Current (VSC-HVDC) technology is an advanced DC transmission technology. The short circuit fault current of VSC system is difficult to break because of its high amplitude and high rate of rise. Appling resistance type Superconducting Fault Current Limiter (RSFCL) is beneficial to VSC-HVDC system. When VSC system works normally, the RSFCL has no effect on the system. However, due to the resistance of RSFCL will be large after the complete quench, RSFCL can reduce the amplitude of the short-circuit current, reduce the decreasing rate of system voltage sag. It will also impact the strategies of failure protection due to large quenched resistance. Because Flexible DC Transmission System of Offshore Oil Production Platform uses VSC-HVDC technology, RSFCL is also useful. In this paper, the basic working principles of RSFCL and Offshore Oil Production Platform are described. The performance of DC circuit breaker is not good in high pollution environment, RSFCL can limit short circuit current and is less affected by the environment. So it is a good idea to combine RSFCL with DC circuit breaker in this condition. Then, referring to the parameters of China National Offshore Oil Corporation (CNOOC) Wenchang Flexible DC Transmission System and RSFCL, a simulation model of this system based on PSCAD/EMTDC is built. The results show that when the flexible DC system works normally, the RSFCL operates at a steady state and low loss, has no obvious influence on the system. When there is a short circuit fault, the impedance of the RSFCL increases. The RSFCL will limit the short circuit current to 2.33 times of the rated current and effectively delay the system voltage sag. The DC voltage of Flexible DC Transmission System of Offshore Oil Production Platform without RSFCL drops rapidly to 0 V within 7ms after short-circuit fault occurs. But after appling RSFCL, the DC voltage recovers to more than 80 % of its peak , so the converter stations will not blocking.