A hybrid method for Critical Clearing Time evaluation of multi-machine systems

This paper proposes a hybrid Critical Clearing Time (CCT) evaluation method. This method is based on an integrated approach of Bisection and Single Machine Equivalent (SIME) technique.In this method initially a time interval in which actual CCT lies is identified followed by applying bisection method for estimation of exact CCT. The method uses SIME based rotor-speed early stop criteria for detection of first-swing stability, thus reducing the computation time required. The hybrid technique is applied to WSCC 9 bus, IEEE 14 bus, IEEE 30 bus and New England 39 bus test system. The obtained CCT results are compared with the results of conventional Time Domain Simulation (TDS) approach. The proposed Bisection and SIME based integrated approach computes the CCT faster compared to conventional TDS approach.