A Method to Enhance the Accuracy of Distance Protection Modeling in Transient Stability Simulations

Abstract

In this paper, it is proposed the use of a method for stability analysis based on combined stability and short circuit simulations. This approach allows augmenting the positive sequence representation and the use of more accurate relay models in stability simulations. As most of well known relay models are available in short-circuit programs, usually provided by the manufacturers, the proposed method allows using directly these models from short circuit programs in the stability analysis. Another important feature of the approach is that when the protection is represented in a short circuit program, it is possible to calculate the relay negative and zero sequence currents due to unbalanced faults, which provides a high-fidelity simulation of the protection actuation. The method was implemented and used for studying events in a model from a system operator planning environment. In the short circuit program, the manufacture's IED parameters were used for the distance protection model, while the typical representation of this relay was used in the stability program. The results allowed verifying that the method was able to identify an instability case, that would not be identified using only the stability program. Recorded data from a unbalanced short-circuit is also compared with simulation results using the method. It has been demonstrated that the use of combined simulations was able to improve the dynamic response fidelity to the recorded data compared with the use of only phasor-based simulation.