EFFECTS OF FLEXIBLE AC TRANSMISSION SYSTEM (FACTS) ON THE PERFORMANCE OF DISTANCE PROTECTION RELAYS

Flexible AC Transmission Systems (FACTS) are power electronic based devices and other static equipment that provide control of one or more AC transmission system parameters to enhance controllability and increase power transfer capability of power systems. FACTS devices are therefore being increasingly employed in power system networks to satisfy these requirements. An additional requirement to preserve power system stability and security is that the power system protection should be dependable and stable, since existing power system protection devices were designed before the advent of FACTS devices it is therefore necessary to investigate the impact they will have on traditional forms of protection. The research study examines the effects of STACOM on distance protection relays. The research work aims to validate a particular model of STATCOM for protection study purposes, and to investigate the effects of STATCOM on distance relay. The objectives set about in this research work are to identify the causes of distance relay mis-operations, to propose corrective actions in order to prevent the mis-operations, and to make recommendations on the area of future research works as an outcome of the research work. The principle conclusions from this works are, at 220 KV level or at similar levels with system that are solidly-grounded, distance relay will fail to operate correctly for higher fault resistances involved in faults beyond the location of STATCOM. The operating times of the distance relay is also higher whenever STATCOM is in service.