GECM-Based Voltage Stability Assessment Using Wide-Area Synchrophasors

Abstract

Voltage instability is a crucial issue in the secure operation of power grids. Several methods for voltage stability assessment were presented. Some of them are highly computationally intensive, while others are reported not to work properly under all circumstances. This paper proposes a new methodology based on the generator equivalent circuit model (GECM) and the phasor measurement unit (PMU) technology for online voltage stability monitoring of a power grid. First, the proposed methodology utilizes synchronized phasor (synchrophasor) measurements to determine the impedance parameters of a transmission grid by means of the recursive least squares (RLS) algorithm. Furthermore, it incorporates the dynamic models of generators to handle the cases with generator reactive power limit violations. After that, an enhanced voltage stability index with GECMs incorporated is developed for reliable and accurate voltage stability assessment. The proposed methodology was first demonstrated on several standard IEEE power systems, and then applied to a practical power system, the Taiwan power (Taipower) system. The test results demonstrate the flexibility and effectiveness of the proposed methodology.

Keywords

• generator equivalent circuit model
• online security assessment
• phasor measurement unit (PMU)
• smart grid
• voltage collapse
• voltage instability
• wide-area measurement system (WAMS)