Evaluating the Influence of Momentary Cessation Mode in Inverter-Based Distributed Generators on Power System Transient Stability

The responses of an inverter-based distributed generator (IBDG) to abnormal voltage and frequency are different from those of a conventional generator because of the inverter's operating modes. In particular, although the momentary cessation (MC) mode is essential to protecting the distribution system, the MC mode can affect the power system transient stability by temporarily ceasing significant amounts of IBDG generation. To mitigate these negative effects, this study analyzed the impacts of MC capability on the power system transient stability. First, the transient stability was analyzed in relation to MC capability using the single-machine equivalent (SIME) method. A critical MC operating point (CMCOP) was then proposed to assess the severity of a transient impact and to secure the transient stability under the contingency conditions. A case study based on the Korean power system validated the feasibility and effectiveness of the proposed method.