A Generalized Short Circuit Ratio for Multi-Infeed LCC-HVDC System

TL;DR

This paper introduces a generalized short circuit ratio (gSCR) for multi-infeed LCC-HVDC systems, providing a quantitative measure of AC system strength related to voltage stability, validated through simulations.

Contribution

A novel gSCR concept is proposed to evaluate AC system strength in multi-infeed LCC-HVDC systems, overcoming limitations of existing methods.

Findings

gSCR effectively measures AC system strength.

Critical values CgSCR=2 and BgSCR=3 differentiate system strength.

Simulations confirm the validity of the gSCR approach.

Abstract

The relationship between the short circuit ratio (SCR) and static voltage stability is analyzed in this paper. According to eigenvalue decomposition method, a novel concept named generalized short circuit ratio (gSCR) has been proposed for multi-infeed LCC-HVDC (MIDC) systems to mathematically measure the connect-ed AC strength from the point view of voltage stability, which can overcome the rule-of-thumb basis of existing multi-infeed short circuit ratio (MISCR) concept. In gSCR, two indices, the critical gSCR (CgSCR) and the boundary gSCR (BgSCR) are developed to quantitatively evaluate if the connected AC system is strong or weak, in which CgSCR=2 and BgSCR=3 are two critical values for strength evaluation. Finally, numerical simulations are conducted to validate the effectiveness of the proposed gSCR concept.