Active boundary identifying technique for steady-state security distance assessment

Steady-state security operation is of particular concern to power systems. In order to ensure operation security, system operators have to operate the system with moderate security margins to accommodate various unpredicted uncertainties. In this paper, we apply “steady-state security distance” (SSD) to quantitatively assess the scale of system security margins. SSD is defined in steady-state security region (SSR) based on AC power flow model. Solution of SSD could be formulated as a time-consuming nonlinear optimization problem. A novel algorithm based on active boundary identifying technique is proposed to improve computation efficiency. The algorithm firstly solves SSD based on simplified DC power flow model and identifies active SSR boundaries. Secondly, complete SSD calculation based on AC power flow model is carried out towards only the active boundaries, with DC SSD information as initial estimations. An IEEE-30 bus case is employed to testify the efficiency and effectiveness of the algorithm.