Improved Thévenin equivalent methods for real-time voltage stability assessment

Abstract

Abstract-An improved Thévenin equivalent method for realtime voltage stability assessment that uses wide-area information from synchrophasors is proposed. The improvements are a better modeling of the limited synchronous generators, and a processing that anticipates the effect of field current limiters, before the latter are activated. Several study cases using detailed dynamic simulations of the Nordic test system have been used to assess the performance of the proposed improvements. Their effectiveness is analyzed and, based on the results, their possible application in combination with the sensitivity-based voltage stability assessment method is explored.

Voltage stability assessment accounting for non‐linearity of Thévenin voltages

“…This shows the necessity of considering the non-linearity of the Thévenin voltage seen from the load, in order to more accurately detect voltage instability. The active load margins determined by (12) provide useful information about the distance to instability and they can be visualised to monitor the system stability in real-time. Figs.…”

“…Improvements to Thévenin equivalent methods have been proposed in recent research. In [12] the activation of overexcitation limiters (OXLs) is anticipated to more accurately determine the maximum deliverable power to the load. In [13] one of four possible operating states of a generator is modelled as an impedance and included in the network to determine the MPT to the load.…”

Real-Time Voltage Stability Assessment Method for the Korean Power System Based on Estimation of Thévenin Equivalent Impedance

“…The authors of Reference [34] have developed a TE method according to a least-squares procedure to determine the parameters from local measurements. In the study by Angel Perez et al, an improved TE method for real-time voltage stability assessment using wide-area information from PMUs was proposed [35]. PMU measurements have been used in Reference [36] to estimate the relative VSM of the affected load buses.…”

Improved Voltage Stability Boundary Monitoring by Accounting for Variations in Thevenin Voltage Magnitude

“…One approach found fitting for real-time assessment of voltage stability for longterm cases was based on the Thevenin Equivalent Method This work is part of the Danish research project Security Assessment of Renewable Power Systems (SARP), which was received funding from the Danish TSO Energinet.dk as part of their ForskEL-programme 978-1-5386-4505-5/18/$31.00 c 2018 IEEE (TEM) [11]- [13]. Several improvements to the TEM approach were investigated, which considered synchronous generator limits, wind-farm limits and the impact an HVDC interconnection has on voltage stability [14]- [16].…”