Review of SIR Calculations for Distance Protection and Considerations for Inverter-Based Resources
Source-to-line Impedance Ratio (SIR) is a parameter used in the application of distance protection. IEEE Std C37.113-2015 (Line Protection Guide) presents a method to calculate SIR for three-phase faults and single-line-to-ground faults. This method has been incorporated into short-circuit programs and is used by practitioners. However, the method uses assumptions that produce erroneous results in systems with zero-sequence mutual coupling and in systems with inverter-based resources. This paper reviews the evolution of SIR calculations (methods) and advocates the use of newer and simpler SIR calculations that remain accurate for all distance protection applications.
Email Address of Submitting Authorritwik_chowdhury@selinc.com
ORCID of Submitting Author0000-0001-8413-9840
Submitting Author's InstitutionSchweitzer Engineering Laboratories, Inc.
Submitting Author's Country
- United States of America