Impact of converter‐interfaced renewable generations on breaker failure protection of the emanant transmission lines

Abstract

Abstract The presence of Converter Interfaced Generations (CIGs) poses significant challenges to traditional protection schemes. This paper studies the impact of CIGs on the Breaker Failure Protection (BFP) of transmission lines emanating from CIGs. The instantaneous over‐current (50BF) setting and reset time of BFP have been investigated. Fault current contribution of CIGs is usually comparable with load currents. Low fault current contribution by CIGs may lead to significant loss of security of BFP because of the existing practice of using lower setting for 50BF. This paper proposes a voltage‐dependent adaptive setting of 50BF element to enhance the security of BFP schemes while maintaining dependability. Use of voltage helps in differentiating loads from fault situations. In traditional power systems, CT subsidence current is known to delay the reset of BFP schemes. The impact of low fault contribution by CIGs on the reset time of BFP has been studied. Mathematical expression for CT subsidence current, which influences the reset time, has been derived. It is observed that the BFP reset may not be delayed if the fault current seen by the breaker is low due to the presence of CIG. Discussions on the dependability and security of proposed 50BF setting are also presented.

Keywords

• Reliability
• Mathematical analysis
• Power electronics, supply and supervisory circuits
• Power transmission lines and cables
• Power system protection
• Power convertors and power supplies to apparatus