Abstract: High penetration of photovoltaic (PV) generation reduces system strength and introduces voltage control, power quality, and transfer capacity constraints across transmission and distribution networks. This review comparatively examines the operating principles, control mechanisms, dynamic response, and deployment implications of key FACTS devices that include: TCSC, TSSC, SVC, STATCOM and SSSC together with Synchronous Condensers. The comparison is organized around a common analytical perspective comprising reactive-power controllability, response speed, voltage support capability, short-circuit contribution, oscillation damping, and practical implementation considerations. The review shows that converter-based shunt devices provide very fast reactive current support and effective voltage regulation but contribute to limited fault current and may require harmonic mitigation; series controllers primarily enhance transfer capability and damping through manipulation of line reactance or injected series voltage. Synchronous Condensers remain particularly valuable where inertia, fault-level support and strong grid behaviour are required, although with higher losses, larger footprint and greater maintenance burden. On this basis, the paper provides technically grounded guidance on matching device type to grid need and on the coordinated deployment of electronic and rotating compensation in high-PV systems.

Keywords: FACTS, STATCOM, SVC, SSSC, TCSC, Synchronous Condenser, reactive power, system strength, power quality

Pages: 240-267