Applied the Software of MATLAB to Calculate the Critical Clearing Time in Power System

Aims: to avoid improper critical clearing time values due to clerical errors during the artificial calculation process, so that takes advantage of MATLAB application software to compile with those equations such as power angle, swing equation, equal area criterions, etc. to calculate of critical clearing time.

Study Design: This article starts introduction with what the way of the calculation such as power angle, swing equation, equal area criterions, etc in literature, and referred lots of the latest literature to develop.

Place and Duration of Study: The setting of the critical clearing time plays an important role in the power system. The start-up time of any protection relay must be shorter than the critical clearing time; otherwise the fault will expand and cause serious damage when the system fails. Therefore, it is an important question the set time of the protection relay needed to caution in planning design.

Methodology: To use MATLAB application software links with above equations to compile the program the calculation of critical clearing time.

Results: The program has been proved very effective and accurate for calculating the reasonable setting value of proportion relay, the same time it would shortened of assignment time by design planners.

Conclusion: Computerized operating procedures can be used to avoid improper critical clearing time values due to clerical errors during the artificial calculation process.