Improved method of quantitative steady-state security assessment based on fast elimination of redundant transmission capacity constraints

Steady-state security analysis is of great importance to power systems. Steady-state security region (SSR) is a region-wise method that could improve the efficiency of steady-state security analysis. Based on SSR, steady-state security distance (SSD) was proposed in literature and SSD provides a quantitative tool for security assessment on a current operation point (OP) or operational state. However, a large scale optimization problem with many constraints must be solved when calculating SSD. In this paper, an improved method for calculating SSD is presented based on fast elimination of redundant transmission capacity constraints. The main idea is to use an analytic method instead of solving an optimization problem to get an over estimation on the maximal power flow on each transmission line, and then compare the result with the line capacity to identify whether the constraint is redundant. By using this method, the problem for calculating SSD is greatly simplified. Numerical tests are performed and the results are satisfactory.