The proposed severity-adapted fault clearing strategy (SA-FCS) employs mechanical DC circuit breaker (DCCB) at each line end and at each converter station DC output. Low value DC limiting reactors (DCR) are also installed in series with the DCCBs. In the proposed SA-FCS different protection sequences are applied depending on the fault characteristics such as fault distance and fault resistance. The faults are thus classified into low impact faults and high impact faults.
Compared to a Full-selective strategy, the proposed strategy uses cost effective mechanical DC breaker instead of ultrafast hybrid DC breaker and lower value of DC limiting reactor which further reduces the cost and the risk of DC voltage dynamic instabilities. The proposed strategy is able to selectively eliminate the fault for most of the OHL faults with a similar power restoration time equal to a full-selective strategy.
Interline Power Flow Controllers