Flux Linkage Based Evaluation Method for Voltage Inertia and Voltage Recovery Capability Under Large Disturbances

TL;DR

This paper introduces flux linkage-based indexes to evaluate voltage inertia and recovery capabilities during large disturbances, aiding in system planning and reactive power dispatch for enhanced voltage stability.

Contribution

The paper proposes two novel flux linkage-based indexes for assessing voltage inertia and recovery, linking them to voltage nadir and recovery speed, with validation on IEEE 39-bus system.

Findings

Indexes effectively quantify voltage support capabilities.

Minimum voltage support requirements for system security.

Validation through IEEE 39-bus system simulations.

Abstract

High-voltage direct current (HVDC) transmission applications and the growth of the dynamic load in large-scale receiving-end grids lead to a higher risk of short-term voltage instability. An effective way to address this problem is to improve the system's dynamic voltage support capability by changing the operation status of dynamic var devices, and the dynamic var reserve (DVR) is commonly used. Due to the time delay in synchronous machine excitation systems, the dynamic var reserved at steady state cannot be exploited immediately under large disturbances. In addition, some reactive power is produced immediately through electromagnetic induction. The voltage support effect of the two capabilities is analyzed based on the flux linkage and an approximate simulation of the fault impact. Then two novel indexes for evaluating the voltage inertia and voltage recovery capability are proposed, which are related to the voltage nadir and voltage recovery speed. The indexes' physical meanings are revealed by comparison with the frequency response, and the potential applications in planning and optimal reactive power dispatch (ORPD) are introduced. Numerical simulations based on the IEEE 39-bus system verify that the indexes can quantify the voltage support capabilities, and the minimum voltage support requirements are obtained to maintain systems' security.