This Deliverable covers the results of ICOEUR Sub-Task 4.1.2 – “Methods and tools for assessing the stability of large power system interconnection”. The Report consists information about small-signal stability analysis methods which can be used for rapid stability analysis of large power system: checking of roots of algebraic polynomial of systems of algebraic equations, new general approach to analyze static stability of differential or algebraic Lyapunov and Sylvester equations. For large disturbance stability analysis, following methods are suggested: transient’s simulation with using parallelization in computation, stability analysis based on structure of electromechanical oscillations. Architecture of software prototype for online stability assessment is presented. This architecture can be used as a part of emergency control software prototype.