An adaptive prefilter algorithm for real-time cyclic security analysis

Security analysis is an important task in modern power system control centers. Security considerations must allow for both active power problems (thermal limits) and reactive power problems involving nodal voltages (isolation and stability limits). There is a definite need for new methods capable of ensuring that system security limits will not be exceeded when abnormal conditions arise, applicable in the real time environment. In this paper, a general algorithm for automating cyclic security analysis is discussed. The algorithm developed uses data obtained from previous security analysis and filters out nondangerous contingencies with reduced computation time. The proposed method may be used to improve speed-up of existing contingency algorithms. Tests have been performed, on the French 225-400 kV grid containing 462 nodes and 855 branches. For this system 96 real states were analysed over a 24-hour-period in 15-minute-steps, These states were recorded on 19 January 1994 on the French grid. The tests confirm that our approach is both applicable and accurate.