Localization of the roots of the characteristic polynomial (CP) and isolines to analyze static stability

The market economy dictates the terms of unification of the energy systems of the countries that leads to a change in number of interconnections, the increase of the transmitted power, and therefore, it is necessary to reconfigure the networks and, consequently, the recalculation of their normal modes, as well as the project assessment of static stability is required. Stability is an important constraint in power system operation and control. Power system stability is understood as the ability to regain an equilibrium state after being subjected to a physical disturbance. A key method among those of static stability analysis is the determination of system stability on the consideration of eigenvalues in steady state condition. This provides appropriate strategy to have a quick decision on the system's steady state behavior. The configuration of the electrical systems should be often changed in terms of market relations. The research is aimed to overcome the difficulties while dealing with the characteristic polynomial of a higher degree. Latvian power systems static stability is evaluated applying the methods of localization of the roots of the CP and isolines.