AUTHOR=Baleboina Guru Mohan , Mageshvaran R. TITLE=A survey on voltage stability indices for power system transmission and distribution systems JOURNAL=Frontiers in Energy Research VOLUME=Volume 11 - 2023 YEAR=2023 URL=https://www.frontiersin.org/journals/energy-research/articles/10.3389/fenrg.2023.1159410 DOI=10.3389/fenrg.2023.1159410 ISSN=2296-598X ABSTRACT=Voltage stability is a critical aspect of power system operation, ensuring the reliable and efficient delivery of electrical energy to consumers. Recently, voltage stability in the power system has received much attention. The primary cause for the voltage instability is the lack of real and reactive power generation to cope with the continuous demand increment. Maintaining voltage stability while planning, controlling, and assessing the system's security is a difficult task for power system engineers. From the knowledge of past incidents, lack of reactive power is identified as the primary cause of voltage instability which may further lead to the total collapse of the system. The importance of voltage stability assessment is essential to maintain the integrity of power systems. It helps prevent voltage instability, which can lead to cascading failures and widespread outages. This paper considers various parameters, including load demand, generator capacity, system impedance, are used to develop the VSIs. and mainly focuses on the idea of voltage stability indices (VSIs) that have been developed in order to monitor and control the criticality of the power system. The voltage stability indices for Transmission and Distributed systems, as well as their subclasses, have been thoroughly reviewed in this study. Furthermore, the traditional voltage stability methods, as well as various software tools for monitoring the voltage stability problems, were also discussed. In addition, the development of VSIs and its concepts have been described clearly in this paper. This comprehensive survey provides a decent groundwork for future work in this area and assists professionals in selecting the optimal VSI for various applications. And also, provides a concise overview of the methods and importance of voltage stability assessment in both transmission and distribution systems.