Critical Review of HVDC and FACTS Technologies for Voltage Stability Enhancement and Grid Sustainability in the Nigerian 330Kv Network

Abstract

Voltage stability and a sustainable power infrastructure are crucial concerns in Nigeria’s 330 kV transmission system because of long transmission distances, weak interconnections, insufficient reactive power reserves, and growing incorporation of renewable energy sources. This paper offers a systematic and in-depth review of the High Voltage Direct Current (HVDC) and Flexible AC Transmission Systems (FACTS) as one of the possible solutions to the challenges. This paper discusses the working principles, type, and characteristics of control of HVDC and FACTS devices with specific reference to how HVDC and FACTS can be utilized to enhance the wheeling capacity of transmission lines, voltage and power flow control, and voltage stability. A systematic review approach is used to explore the more recent literature. It pays attention to major developments, the characteristics of comparison with the performance, and its applicability to weak and developing power systems. In addition, the paper also defines the applicability of these technologies in attaining sustainable development goals through enhancing grid stability, minimizing transmission losses, and facilitating versatile and robust power system operation. The results show that Voltage Source Converter (VSC)-based HVDC systems are better in terms of controllability, effective long-distance power transmission, and integration of renewable energy, whereas FACTS devices like STATCOM, SVC, and UPFC are effective in offering reactive power compensations quickly and dynamically in AC networks. Despite these advantages, several research gaps are identified, including limited Nigeria-specific implementation studies, a lack of coordinated HVDC–FACTS control strategies, and an insufficient techno-economic evaluation framework.