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Yang D.,TU Dortmund | Yang D.,Institute of Power Systems and Power Economics | Rehtanz C.,TU Dortmund | Rehtanz C.,Institute of Power Systems and Power Economics | And 3 more authors.
Przeglad Elektrotechniczny | Year: 2012

This paper presents a novel method for denoising and detrending of oscillatory signal measured from wide area measurement system (WAMS) using empirical mode decomposition (EMD) and time-frequency analysis. First of all, the measured signal is decomposed into a set of intrinsic mode functions (IMFs) by EMD. Next, the IMFs are divided into three parts based on their time and frequency distributions. Then, the noise and higher frequency components, trend components and meaningful oscillation modes are identified respectively. The proposed method are validated by the actual measured signal from WAProtector and the estimated trend is confirmed by comparing with the sliding linear trend estimated method and other nonlinear trend estimated methods.

Li Y.,Hunan University | Li Y.,Institute of Power Systems and Power Economics | Zhang Z.,Hunan University | Rehtanz C.,Institute of Power Systems and Power Economics | And 3 more authors.
IEEE Transactions on Power Electronics | Year: 2011

Different from the main circuit topology of the traditional current source converter (CSC)-based HVdc transmission system, this paper proposes a new CSC-HVdc transmission system based on a new inductive filtering method. Such new HVdc system characters as a new main circuit topology and mainly contains a new converter transformer and related full-tuned (FT) branches. With regard to the implementation conditions of the new inductive filtering method, the basic main circuit parameter design for the new converter transformer, the related FT branches, and the HVdc control system are presented, respectively. Based on these designed main circuit parameters and control system, the new CSC-HVdc system is modeled in the PSCAD/EMTDC environment, and correspondingly, through comparative study with the International Council on Large Electric Systems (CIGRE) HVdc benchmark model, the steady-and the transient-state operating characteristics of the new CSC-HVdc system are studied in detail. The research results show that the new CSC-HVdc system can widen the stable operating range, increase the dc transmission capacity, and meanwhile, improve the commutating performance of the CSC-HVdc converter. Moreover, it maintains the stable operating performance and represents the good fault-recovery ability when suffering the typical faults (e.g., single-phase or three-phase faults at the rectifier and the inverter side of the HVdc transmission system). © 2011 IEEE.

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