The demand of electricity is continuously increasing. There are interconnections of power systems which are located at different places. Due to weak interconnection between tie lines, there are oscillations in the power system which affect the stability of the power system. There are oscillations of active power in power transmission systems particularly during heavy power transfer. Such oscillations can be excited by a number of reasons such as line faults or a sudden change of generator output. Due to the presence of active power oscillations, there are limitations of power transmission capacity. It is often possible to find remedy by building additional lines or upgrading existing lines, but this cost a lot of money and takes a lot of time. In some cases, it may also be possible to introduce power system stabilizers (PSS) on generators, but this will not always work, particularly not for inter-area power oscillations, which tend to be of a low frequency (typically 0.2 Hz to 0.7 Hz). In this condition, a FACTS device called Thyristor-Controlled Series Compensation (TCSC) will be an attractive alternative to consider. It provides a cost-effective, robust power oscillation damper, insensitive to its location in the system and it is noninteracting with local oscillation modes. In a number of cases, it will turn out to be the best practicable solution.