Abstract
The simultaneous implicit approach proposed in [1] has become the state-of-the-art for transient stability simulation.The associated algorithm results in considerable saving in CPU time and elimination of interface errors between the set of algebraic equations of the network and the synchronous machines,and the set of differential equations of synchronous machines and associated control systems. In this paper, certain significant changes are proposed to this approach, with the aim of speeding up the algorithm without sacrificing accuracy. These changes are (i) convergence criterion based on generator real power output rather than rotor angle, (ii) a two-tier approach for the iterative solution of algebraic and differential equations, and (iii) better corrector formula for rotor angle [2]. Preliminary tests on a standard test system, reveal that the number of network solutions required for convergence per time step can be reduced by half. This feature of the algorithm provides ample scope for reduction in the computation time required for transient stability simulation of large scale power systems. The algorithm yields stable solutions at uncommonly large step sizes and thereby finds potential application in real time simulation involving individual generator dynamics.