Research on vibration characteristics and Multi-parameter state recognition of ± 500 kV converter transformer under fluctuating conditions

• The load and no-load tests under fluctuating operating conditions are designed, and the vibration measurement scheme of winding and iron core of converter transformer is constructed. • The influence of state fluctuation on vibration characteristic distribution is considered from time domain, frequency domain and energy domain. • Based on the difference of vibration characteristics under different working conditions, a converter transformer operating state identification method fused with multiple characteristic parameters is proposed, which effectively solves the limitation of single characteristic identification. The vibration of the winding and the iron core is the main source of the vibration of the converter transformer tank, and the vibration measurement and characteristic analysis are the judgment basis for its condition monitoring and identification. Compared with AC transformers, the vibration mechanism and vibration characteristics of converter transformers under fluctuating operating conditions are imperfect. Aiming at the special tank structure and considering the fluctuation of operating conditions, this paper establishes a multi-channel vibration measurement system for online identification of the operating status of the converter transformer, and extracts the characteristics parameters of the vibration signal in the time domain, frequency domain, and energy, and analyzes the differential distribution characteristics of winding vibration under different load currents, iron core vibration under different no-load voltages, and combined vibration during online rated operation. Finally, a method for identifying the operating status of converter transformers based on multi-characteristic parameters is proposed. The research results show that the characteristic parameters such as tank vibration intensity, maximum vibration frequency, and frequency band energy fluctuate with the operating status of the converter transformer, and there are obvious changes. Vibration measurement and characteristics of multi-characteristic parameters can be used to provide a theoretical basis and solution ideas for the operation status identification and early fault detection of converter transformers.