Fast and Reliable Method of Searching Power System Marginal States

In order to maintain power system security at the appropriate level and low cost, it is essential to accurately assess steady-state stability limits and power flow feasibility boundaries, i.e., power system marginal states (MS). This paper is devoted to a robust realization of the MS model based on nonlinear programming in a given direction of power change. Considering peculiar properties of this model has allowed proposing a simple, robust and computationally efficient method of the MS search that uses only standard blocks of the load flow solution and can be easily realized in the existing load flow programs. The technique developed on this basis allows considering errors of power change forecast quite easily. Tests on IEEE and Russian systems showed effectiveness of the proposed methods.