Dynamic simulation of voltage instability with particular reference to protection strategies using EMTP

The simulation of voltage instability and voltage collapse can be basically classified into static simulation and dynamic simulation; initially, the static simulation was the one used. The static method requires less CPU resource, provides the voltage stability indices and gives much insight into the voltage and the power problem. However, this is a less accurate method than the dynamic simulation performed in the time domain. When it becomes difficult to secure the voltage stability margin via the static stability simulation approach, it becomes necessary to perform the dynamic simulation; in this case, it is required to model the dynamic components of the power system such as a generator and a load. The dynamic simulation provides the accurate results of the voltage instability. However, this method also has some drawbacks in that, it cannot provide the sensitivity information and the margin of the stability, is time consuming and needs much CPU resource. Nonetheless, system transient stability studies based on dynamic simulation are important in order to ascertain the protection/critical fault clearance time strategies that need to be adopted. This paper uses EMTP MODELS to perform a dynamic simulation of voltage instability and voltage collapse. The load model is implemented with EMTP MODELS and this model is then interfaced with a test power system. The test results clearly show that we can simulate the voltage instability and the voltage collapse dynamically using EMTP MODELS.