Semi-Implicit Formulation of Differential-Algebraic Equations for Transient Stability Analysis

The paper proposes a semi-implicit formulation of the differential-algebraic equations (DAEs) describing power system models for transient stability analysis. This formulation, if coupled to an implicit integration scheme, shows two relevant advantages with respect to the conventional explicit formulation: (i) reduce the computational burden; and (ii) increase the sparsity of the Jacobian matrix of the system. The proposed model also allows using null time constants and thus simplifies the computer implementation of the DAEs. The properties and the performance of the proposed semi-implicit formulation and the conventional explicit one are compared through a dynamic 21,177-bus model of the European transmission system.