Stability Enhancement of Islanding Event Through Boundary Detection and Voltage Stability Index

The use of distributed generation (DG) in distribution system is on the rise. In some setups, DG enables the distribution systems to operate in autonomous mode. However, this mode is not widely utilized due to safety and stability issues. This paper presents a scheme that facilitates the distribution system to maintain stability when transitioning to autonomous mode. Firstly, boundary detection method is proposed to determine the topology of the island formed. Next, voltage collapse prediction index (VCPI) is adopted to determine the stability state of each bus in the islanded system. For the third step, a stability enhancement scheme based on VCPI to shed the critical bus for stabilizing the system is proposed. The proposed scheme is simulated in a generic 9-bus system via EMTDC/PSCAD and MATLAB software operating in parallel. Results show that the proposed scheme can identify the island topology accurately and maintain voltage stability post-islanding.