THEORETICAL FOUNDATION OF THE BCU METHOD FOR DIRECT STABILITY ANALYSIS OF NETWORK-REDUCTION POWER-SYSTEM MODELS WITH SMALL TRANSFER-CONDUCTANCES

The controlling unstable equilibrium point (u.e.p.) method is consider ed to be the most viable for direct stability analysis of practical po wer systems, The success of the controlling u.e.p. method, however, hi nges upon its ability to fmd the (correct) controlling u.e.p. Recently , a systematic method, called boundary of stability region based contr olling unstable equilibrium point method (BCU method), to find the con trolling u.e.p. was developed, The BCU method has been evaluated in a large-scale power system and it compared favorably with other methods in terms of its reliability and the required computational efforts, In this paper, a theoretical foundation of the BCU method for the networ k-reduction classical machine stability model is developed, Sufficient conditions for the BCU method to find the correct controlling u.e.p. relative to a given fault are derived.