A new transfer impedance based system equivalent model for voltage stability analysis

•An accurate model of power system is critical for any voltage stability analysis.•A new transfer impedance based system equivalent model (TISEM) is developed.•The TISEM can calculate transfer impedance and power from generators to loads.•The TISEM-based voltage stability index accurately identifies the weakest nodes.•Compared to the eigenvalue method, the TISEM based method can be 25 times faster.

This paper presents a new transfer impedance based system equivalent model (TISEM) for voltage stability analysis. The TISEM can be used not only to identify the weakest nodes (buses) and system voltage stability, but also to calculate the amount of real and reactive power transferred from the generator nodes to the vulnerable node causing voltage instability. As a result, a full-scale view of voltage stability of the whole system can be presented in front of system operators. This useful information can help operators take proper actions to avoid voltage collapse. The feasibility and effectiveness of the TISEM are further validated in three test systems.