Controlled network splitting considering transient stability constraints

Abstract

Intentional islanding has been extensively studied recently as the last resort to prevent blackouts, mostly from the perspective of thermal static constraints satisfaction. However, as most previous studies on this topic do not address stability issues, their controlled islanding plans might fail to ensure the stability of resulted islands, thereby delaying their acceptance and adoption by utilities. This study makes progress towards addressing stability issues, proposing a controlled islanding model that ensures and improves the transient stability of the islanded system. Linear transient stability constraints are derived off-line, based on the extended equal area criterion, to ensure the first swing transient stability of the synchronous machines, just after the controlled line switching. The islanding model with transient stability constraints is first developed as a mixed-integer nonlinear program (MINLP). Furthermore, the MINLP model is linearised, resulting in a computationally lighter mixed-integer linear program. The objective function of the islanding model is to minimise the generation imbalance of islands and to increase the transient stability margin of the resulting islands, and the obtained optimisation results are validated by the fully fledged dynamic simulation. The efficacy of the proposed method is validated by simulation on the IEEE 118-bus system.