Hilbert–Huang Transform Based Transient Analysis in Voltage Source Converter Interfaced Direct Current System
Dongyu Li, Abhisek Ukil, Kuntal Satpathi, Yew Ming Yeap
Abstract
Due to the rapid discharging of the dc-link capacitors, the short-circuit fault normally results in a fast-growing transient current in the voltage source converter (VSC) based dc power system. Therefore, a fast and sensitive fault detection method is required. In this article, the feasibility of Hilbert-Huang transform (HHT) for fault detection in VSC-based high-voltage direct current systems is analyzed. The instantaneous energy density level is used as the fault detection criterion, which emphasizes the fault characteristics in a predefined frequency range and suppresses the effect of steady-state ripple components. The theory of the proposed HHT-based fault detection method is presented in detail. Its effectiveness is tested on an OPAL-RT based multiterminal dc system and a point-to-point experimental dc system. A response delay within 2 ms after the fault inception is achieved. The comparison with other popular frequency-domain based fault detection methods including the wavelet transform, the short-time Fourier transform, the S transform, and the existing HHT-based analysis, using amplitude frequency coefficient as detection criterion, underlines the performance of the proposed method.