DAMPING POWER SYSTEM OSCILLATIONS USING A STATCOM AND A PHASE IMBALANCED HYBRID SERIES CAPACITIVE COMPENSATION SCHEME

Abstract

Interconnection of remotely power systems with large generation capacity and system load is progressively widespread due to the increase of the power exchanges between countries as well as regions within countries in many parts of the world. In the cases of long distance AC transmission, as in interconnected power systems, care has to be taken for maintaining synchronism as well as stable system voltages, particularly in conjunction with system faults and line switching. With series compensation, bulk AC power transmission over very long distances (1000 km and more) is in existence today. These long distance power transfers cause, however, the system low-frequency oscillations, typically within the range of 0.4 to 2 Hz, to become more lightly damped. For this reason, many power network operators and utilities are taking steps to add supplementary controls in their systems to provide extra system damping aiming to improve the system security by damping these undesirable oscillations. This thesis reports the results of time-domain simulation studies that are carried out to investigate the effectiveness of supplemental controls of a phase imbalance hybrid single-phase-Thyristor Controlled Series Capacitor (TCSC) compensation scheme and a static synchronous compensator in damping power system oscillations. In this context, studies are conducted on a typical large power system incorporating several series capacitor compensated transmission lines and large load centers with their reactive power support provided by static synchronous compensators (STATCOM). Several case studies investigating the effects of the location of the hybrid single-phase-TCSC compensation scheme, the degree of compensation provided by the scheme, the stabilizing signals of the supplemental controls, the fault clearing time, as well as the fault location on the damping of power system oscillations are documented. The results of the investigations conducted in this thesis demonstrate that the supplemental controls are very effective in damping power system oscillations resulting from clearing system faults. The time-domain simulation studies are conducted using the ElectroMagnetic Transients program Restructured Version (EMTP-RV).