A Comprehensive Performance Evaluation of Sequence Component based Directional Relaying Philosophies for Inverter Integrated Power System

Increase in the deployment levels of inverter-interfaced renewable energy resources (IIRERs) in the existing power systems have increased concerns among the protection engineers regarding the reliable operation of classical protection schemes presently existing in the system. This paper aims to do a comprehensive performance evaluation of directional relaying philosophies. In this regard, both the inverter control scheme along with the sequence based directional relaying schemes (SBDRS) are modeled in detail in PSCAD environment. The unpredictability observed in the values of sequence component contributions from IIRERs during faults have led to the mal-operations of SBDRS to correctly identify the direction of fault. A comparative assessment of the performance of SBDRS have been done considering contributions from conventional generators and IIRERs, in the presence and absence of grid codes. The performance of positive sequence based directional relaying scheme improves with the inclusion of grid codes with inverter control used being positive sequence current control. The performance of negative sequence based directional relaying scheme mal-operates whereas the performance of zero sequence based directional relaying scheme is dependent on interconnecting transformer connection and type of fault.