A Novel Directional Comparison Bus Protection Scheme based on Fault Current Superimposed Component

In this paper, an innovative directional comparison bus protection (DCBP) scheme based on fault current superimposed component (FCSC) is proposed. Unlike current differential bus protection (CDBP) methods, conventional DCBP schemes not only need current and voltage signals but their performance can be adversely affected by capacitor coupling voltage transformer transients or large voltage drops at the relay location during close-in faults. Furthermore, it is often not possible to implement DCBP schemes in distribution networks due to the absence of a potential transformer, and in any case, due to associated costs, distribution buses are not usually equipped with CDBP or DCBP. To address these problems, a novel FCSC-based directional element has been designed and incorporated into a proposed DCBP scheme. Additonally, an effective countermeasure has been devised to enable the proposed DCBP scheme to maintain its effectiveness during weak-infeed and/or out-of-service feeder circuit breakers. The performance of the proposed scheme has been evaluated under various operating conditions, the obtained results demonstrate its efficacy for bus protection.