Abstract: As renewable energy gradually replaces traditional synchronous generators, the active voltage support it provides has become key to ensuring the security and stability of new type power systems. However, the current understanding of this critical capability remains insufficient, particularly lacking a theoretical framework and metric system for its systematic and quantitative assessment, which hinders the full exploration of its potential and its efficient utilization. To address this research gap, this paper proposes a framework for assessing the active voltage support capability of renewable energy. This framework decouples this complex capability into two core dimensions: intrinsic characterization, which reveals the converter's own control and physical characteristics, and external effects, which reflect its actual performance after dynamic interaction with the power grid. This paper reviews the development history of renewable energy from passive grid connection, grid-friendly operation, weak active support to strong active support, as well as the corresponding control strategies, based on two technical threads: simulating steady-state/quasi-steady-state voltage source characteristics and continuous improvement of fault ride-through (FRT) anti-disturbance capability. It then extracts voltage issues in four typical scenarios and summarizes the corresponding active voltage support requirements and control methods. Subsequently, from the dimension of intrinsic characterization, this paper discusses the evaluation indicators and methods for the active voltage support capability under steady-state/FRT conditions; and from the dimension of extrinsic effects, it presents the corresponding indicators and calculation methods in combination with scenario requirements. Finally, future research directions are outlined, including the aggregated evaluation of power plants' active voltage support capability and the spatiotemporal optimal coordinated control of system-wide multiple reactive power sources.