A Study of Series Capacitor Effects on Total Transfer Capability of the Central-to-Southern Thailand Transmission System

In Thailand, expanding the total transfer capability (TTC) of the transmission system from the central to southern regions poses a challenge due to a bottleneck-like geographical landscape. This paper outlines main steps taken to generate an automated program for studying the effects of a series capacitor on enhancing TTC, considering sub-synchronous resonance (SSR) which could possibly occur as a result of using such a series device. Then it applies the developed program to examine feasibility of increasing the TTC from the central to southern regions of Thailand, taking into account thermal and voltage operational limits, local generation capacities, as well as SSR problems. Test results reveal a significant increase of the allowable transferred power via the existing transmission network with no sign of possible damage associated with SSR on a generating unit. It is also noted that this applied scheme helps reduce inter-area oscillation between those two areas.