Analysis of the System Impact upon Thyristor Controlled Series Capacitor Relocation Due to Changes in the Power System Environment

Owing to geographical and political influences, Korea has an independent electric power system and the highest density of electric power facilities in the world. Large-scale base power generation complexes are located in non-metropolitan coastal areas, while the most expensive combined cycle power plants are operating or under construction in the metropolitan areas, which have the largest electricity demand. It has become difficult to secure a site for power plants, and the existing power transmission network is insufficient because of the additional construction of generators in existing power generation complexes, the increase in capacity of facilities, and the rapid increase in new and renewable energy. In particular, the East Coast region has a problem of transient stability for this reason, which is being addressed in advance through power generation restrictions. In addition, TCSC (Thyristor Controlled Series Capacitor) is installed and operated to expand the capacity of existing power transmission lines and improve stability in the failures of nearby high-voltage lines until new transmission lines that take more than 10 years are installed to resolve power generation restrictions. However, after the construction of a new transmission line, the efficiency of the existing TCSC is degraded, and for efficient use, it is necessary to rearrange the installation location to utilize the optimal TCSC according to changes in the configuration of the nearby power system. Moreover, a detailed analysis is needed on whether the TCSC designed according to the existing grid configuration exhibits accurate control performance even after the relocation and whether it interferes with nearby generators. In addition to the dynamic performance based on real-time simulations, it is necessary to study the control performance and interaction for this power electronic equipment. This study verified the need to change controller parameters, the interaction effect with nearby generators for stable operation, and the system effect of TCSC relocation using the same replica controller as the actual field controller, as well as RTDS (Real Time Digital Simulation) simulating the entire power transmission system.