A Critical Clearing Time Calculation Method Based on Enhanced Binary Search

With the rapid growth of large-scale, long distance high/ultra-high voltage transmission over the past few years, severe faults may cause more serious consequences on power system. A critical clearing time calculation (CCT) method based on enhanced binary search is proposed, in order to ensure the safety and stability of the power grid after the loss of large power supply or load. Based on interpolation formula or curve fitting and under special relating angle limitation, maximum clearing time to be target function, all swing equations in power system will be converted into numerical equivalent algebraic equations by using the implicit trapezoidal rule and are involved in equality constrains set. All rotors’ angles related are considered to inequality constrains. Transient security is strictly evaluated based on the trajectory in time domain. Based on time domain emulating and numerical calculation completely, proposed model and algorithm are suitable for any generator and load modules. Four examples on the IEEE 39-bus system were introduced to verify the effectiveness of the proposed algorithm.