Abstract
With the wide application of power electronic devices and nonlinear loads, the resulting inter-harmonic pollution is becoming more and more serious in the power system. As important equipment in power systems, transformers have always been the focus of research. However, there are few studies on the abnormal increase in vibration and noise caused by inter-harmonic excitation. In this work, a transformer core vibration and noise measurement platform that can generate arbitrary inter-harmonic excitations was built. The real-time vibration displacement waveforms of the core model under normal and inter-harmonic conditions were experimentally measured as well as the surrounding noise level amplitude and spectrum analysis result. The influence law of excitation of intermediate harmonic content and frequency on core vibration displacement and surrounding sound pressure level was summarized. The work of this paper lays a theoretical foundation for studying the vibration and noise of power transformers and other equipment under inter-harmonics.
Highlights
IntroductionPower inter-harmonic refers to any harmonic whose frequency is not an integer multiple of the fundamental frequency, and the inter-harmonic whose frequency is less than the fundamental frequency is usually called sub-harmonic [1]
The inter-harmonic frequency generated by common nonlinear loads is 0~50 Hz; the inter-harmonic frequency generated by the frequency conversion device is a discrete value related to the sum or difference of the input and output side frequencies, the inter-harmonic generated by the sub-synchronous oscillation of the wind turbine
The experimental platform and experimental methods in this paper present, there is little research on transformer core vibration and noise under inter-harmonic can provide a reference on transformer core vibration and noise under inter-harmonic exexcitation
Summary
Power inter-harmonic refers to any harmonic whose frequency is not an integer multiple of the fundamental frequency, and the inter-harmonic whose frequency is less than the fundamental frequency is usually called sub-harmonic [1]. Common main sources are nonlinear loads, inverter speed governors, and sub-synchronous oscillation of wind turbines [2,3], etc. The inter-harmonic frequency generated by common nonlinear loads is 0~50 Hz; the inter-harmonic frequency generated by the frequency conversion device is a discrete value related to the sum or difference of the input and output side frequencies, the inter-harmonic generated by the sub-synchronous oscillation of the wind turbine. The frequency is generally less than the synchronization frequency of
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