Suitability of voltage stability study methods for real-time assessment

Abstract

This paper analyzes the suitability of existing methods for long-term voltage stability assessment for real-time operation. An overview of the relevant methods is followed with a comparison that takes into account the accuracy, computational efficiency and characteristics when used for security assessment. The results enable an evaluation of the run time of each method with respect to the number of inputs. Furthermore, the results assist in identifying which of the methods is most suitable for realtime operation in future power system with production based on fluctuating energy sources.

Improved Thévenin equivalent methods for real-time voltage stability assessment

“…The application of the TEM is thus enhanced and its anticipation capability can be used to prioritize and activate control actions and countermeasures. The limitations of the TEM, identified in [11,13,14], are significantly removed by including the corrections proposed in this paper; it highlights the importance of considering the OELs and the importance of the Nordic system study cases in the development of voltage stability assessment methods.…”

“…• the TEM provides a distance to instability boundary, in the form of (active, reactive or apparent) power margins (as computed by this method); • the sensitivities S QgQi (more precisely their change of sign from a large positive to a large negative value) shows accurately when this boundary is crossed; • the limitations of the TEM, previously identified in [11,13,14], are significantly removed by including the corrections proposed in this paper. Yet, the method can benefit from the complementary indication given by the sensitivities.…”

“…In the specific case of voltage stability [8,9], the Thévenin Equivalent Methods (TEMs) and the sensitivity-based method [10] were identified in [11] as suitable for wide-area real-time monitoring from a control center. Both approaches have low computational complexity, making them suitable for fast realtime applications.…”

“…Both approaches have low computational complexity, making them suitable for fast realtime applications. For a review of existing methods, refer to [11,12].…”

“…Some limitations of the TEMs were identified in [11], after which a number of improvements have been explored, dealing with: synchronous generator limits [13], wind-farms limits [14] and HVDC interconnections [15]. A further set of improvements is presented in this paper, inspired of techniques This work has received funding from the Danish Council for Strategic Research as a part of the project Secure Operation of Sustainable Power Systems (SOSPO) 1 www.naspi.org 2 www.sospo.dk proposed in [16] in complement to the sensitivity computation and monitoring.…”