Effects of STATCOM on the critical clearing time of faults in multi-machine power systems during transient stability analysis studies

An ever-increasing size of the power system transmission networks has made the system to be prone to various disturbances which could result to system instability. Therefore, increasing the critical clearing time (CCT) of faults before necessary actions are taken is of paramount importance to power system operators in order to maintain and enhance the dynamic security of the system. This paper takes an advantage of STATCOM device to increase the CCT of a multi-machine power system. The differential and algebraic equation model (DAE) of the system is used. The generator transient model (2-axis model) is also utilized with excitation and governor dynamic models. IEEE 14-bus test system is used in the analysis done in the MATLAB environment. The disturbance introduced is the loss of transmission line. The CCT of the system is determined without STATCOM in place and after which STATCOM is connected across the terminal buses of the critical line and the simulation carried out again. The critical clearing time was found to increase with STATCOM across either of the terminal buses of the critical transmission line.