Vibration characteristics of ±800 kV converter transformers part I: Under no-load conditions

Abstract

For lack of study on the vibration characteristics of converter transformers, this paper studied the vibration signal analysis method and investigated the vibration characteristics of converter transformers during the commissioning of a ±800 kV converter station. The study comprised two parts including no-load and load conditions. In Part I, converter transformers are under no-load conditions. Vibration data are collected under conditions of no-load closing, no-load voltage rise with converters, and no-load voltage rise with DC lines. The vibration characteristics and mechanisms are studied based on the collected data. Several different vibration characteristics are introduced. Vibration power entropy, vibration total harmonic distortion, and recurrence rate are calculated under no-load conditions. Results show that vibration amplitude, vibration total harmonic distortion, and recurrence rate are sensitive to no-load closing. Vibration power entropy is sensitive to no-load voltage rise with DC lines. All these vibration characteristics are sensitive to converter unlocking. These characteristics show different and significant changes under different no-load conditions. Thus, it is vital to choose appropriate vibration characteristics when assessing the vibration state of converter transformers under different operating conditions. The study examines the vibration characteristics’ physical meanings and their changing mechanisms. It also summarizes distribution intervals and typical values of vibration characteristics. This research reveals the vibration regularity and corresponding mechanism. It provides a reference for vibration state assessment and early fault detection of ±800 kV converter transformers under no-load conditions.

Keywords

• Condition assessments
• Converter transformer
• Monitoring
• No-load conditions
• Vibration