A comparative study of model and measurement based voltage stability approaches

With the increasing complexity and advancements in the power system, several algorithms and tools have been developed to assess the voltage stability using synchrophasor measurements or system model or both. Several new algorithms have been proposed by researchers and some of them have been converted into commercial tools. Most of these algorithms have several advantages, but at the same time also have some limitations. Local synchrophasor measurement based algorithms are generally based on window based approach to estimate system parameters to compute proximity to voltage stability margin. Model based approach is suitable for offline and planning studies but may not be suitable for online real-time implementation. There are limited number of hybrid algorithms using measurements and model both, but more work need to be done to meet the accuracy and time-line requirements. This paper discusses about limitations of the existing online voltage stability algorithms in detail and the reasons for a need of fast and robust online voltage stability algorithm. A number of operating conditions have been modeled and simulated for standard IEEE test systems.