Impact of Secondary Voltage Regulation Dynamics on Transmission-Level Voltage Stability

Abstract

This paper presents a theoretical framework and case studies aimed at assessing the impact of secondary voltage regulation (SVR) on long-term voltage stability at the power transmission level, considering potential interactions with on-load tap changer (OLTC) transformers and generator over-excitation limiter (OEL) protection. The parallel SVR scheme, an alternative to the conventional cascaded design, is thoroughly detailed. Findings are supported by dynamic simulations in Python of a test system tailor-made for voltage stability studies, focused on SVR performance throughout line outage and ramp load increase events. Results show that SVR action is beneficial not only to ensure flat voltage profiles and fair reactive power sharing among generators, but also to mitigate OLTC tap changing and postpone OEL triggering. Discussions pertaining to this work can be of great value to control center operators seeking cost-effective methods to improve daily voltage control routines.

Impact of Secondary Voltage Regulation Dynamics on Transmission-Level Voltage Stability