New oscillation emergence in three-group oscillation mode and its control measure research after islanding

Based on an equivalent system model, new oscillation emergence phenomena of three-group oscillation mode are focused after the traditional separation measure in which new oscillation center distribution character and regularity, its impact on separation measure are studied. The simulation results of Northeast Grid, Northwest Grid, East China and North China Grid of China validated the presented new oscillation center distribution character and regularity. The impact of all kinds of three-group oscillation modes on isolation measure and corresponding counter-measure are discussed in which the traditional oscillation mode of three main out-of-step generator groups, the mode of two main out-of-step generator groups with one minor counter-part and the mode of one main out-of-step generator group with two minor counter-parts are included. Simulation result shows that the major out-of-step interface should be the priority of the three-group oscillation mode islanding strategy.