The mixed Adams-BDF variable step size algorithm to simulate transient and long term phenomena in power systems

A combined simulation of transient and long term phenomena in power systems requires the solution of a large nonlinear stiff set of differential-algebraic equations. In this paper, the authors propose the mixed Adams-BDF variable step size and variable order algorithm for solving this problem. The Adams method is applied to the differential state variables: it provides a more reliable detection of stable cases from unstable cases than BDF. The BDF (backward differentiation formulae) method is applied to the algebraic state variables. These are less sensitive to the variations in algebraic equations than the Adams method. This combined Adams-BDF method has been successfully implemented in the EUROSTAG simulation package and sample results are presented in this paper