Using SSSC based induction machines for indirect toque control during fault

This paper presents a novel control method for an induction machine (IM) connected to the network through the Static Synchronous Series Compensator (SSSC) and parallel capacitor at the IM´s terminals. By segregating the operational states into three sequential operational zones namely, normal (0), during-fault (1), and after-fault recovery (2). Each state provides an appropriate controlling process for SSSC to improve the operation of induction machine. In normal operation the goal is to improve the power flow and transient stability. Fault operation deals with rotor acceleration which is decreased by utilizing SSSC in resistive mode. Recovery state employs the Indirect Torque Control (ITC) concept to improve the electro-mechanical stability. Tuning the parameters of the two operational states mentioned above, (1) and (2), modifying the IM´s terminal voltage and grid side voltage modification according to Low Voltage Ride-Through (LVRT) limitation is possible. The proposed concept has been proved by time domain simulation in MATLAB power system block sets which shows that suggested method has a more robust operation compared to static synchronous compensator (STATCOM) and less electro-magnetic stresses compared to SSSC without ITC.