scholarly journals DFT-Based Identification of Oscillation Modes from PMU Data Using an Exponential Window Function

Energies ◽  
2019 ◽  
Vol 12 (22) ◽  
pp. 4357
Author(s):  
Jin Kwon Hwang ◽  
Sangsoo Seo ◽  
Julian Sotelo Castanon ◽  
Ho-Chan Kim
Keyword(s):  
Power System ◽  
Conventional Method ◽  
Least Squares Method ◽  
Synthetic Data ◽  
Modal Identification ◽  
Window Function ◽  
Long Duration ◽  
Oscillation Modes ◽  
Transient Data ◽  
Exponential Window

The characteristics of oscillation modes, such as interarea, regional, and subsynchronous modes, can vary during a power system fault, which can cause switching and control actions in the power system. Transient data of the modal response due to such a fault can be acquired through phasor measurement units (PMUs). When the transient data have a long duration, it is desirable to perform modal identification separately on each segment of the transient data, so as to reflect the varying characteristics of oscillation modes. A conventional discrete Fourier transform (DFT)-based method for parametric modal identification cannot be efficiently applied to such a segment dataset. In this paper, a DFT-based method with an exponential window function is proposed to identify oscillation modes from each segment of transient data in PMUs. This window function allows the application of the least squares method (LSM) for modal identification in the same manner as the conventional method. The accuracy of identification of the proposed method is compared with those of the conventional method and a Prony method through synthetic data of transient responses. Its feasibility is also verified by identifying real-world oscillation modes from transient data in PMUs.

Unbiased expression of FRF with exponential window function in impact hammer testing

2004 ◽  
Vol 277 (4-5) ◽  
pp. 931-941 ◽  
Author(s):  
Se Jin Ahn ◽  
Weui Bong Jeong ◽  
Wan Suk Yoo
Keyword(s):  
Window Function ◽  
Exponential Window

Simultaneous inversion of Q and reflectivity using dictionary learning

Geophysics ◽  
2021 ◽  
pp. 1-69
Author(s):  
Jie Shao ◽  
Yibo Wang
Keyword(s):  
Conventional Method ◽  
Dictionary Learning ◽  
Computational Efficiency ◽  
Synthetic Data ◽  
Inversion Method ◽  
Learning Method ◽  
Q Value ◽  
Value Set ◽  
Simultaneous Inversion ◽  
Convolution Model

Quality factor ( Q) and reflectivity are two important subsurface properties in seismic data processing and interpretation. They can be calculated simultaneously from a seismic trace corresponding to an anelastic layered model by a simultaneous inversion method based on the nonstationary convolution model. However, the conventional simultaneous inversion method calculates the optimum Q and reflectivity based on the minimum of the reflectivity sparsity by sweeping each Q value within a predefined range. As a result, the accuracy and computational efficiency of the conventional method depend heavily on the predefined Q value set. To improve the performance of the conventional simultaneous inversion method, we have developed a dictionary learning-based simultaneous inversion of Q and reflectivity. The parametric dictionary learning method is used to update the initial predefined Q value set automatically. The optimum Q and reflectivity are calculated from the updated Q value set based on minimizing not only the sparsity of the reflectivity but also the data residual. Synthetic data and two field data sets were used to test the effectiveness of our method. The results demonstrated that our method can effectively improve the accuracy of these two parameters compared to the conventional simultaneous inversion method. In addition, the dictionary learning method can improve computational efficiency up to approximately seven times when compared to the conventional method with a large predefined dictionary.

Numerical Resolution Enhancement of X-ray Diffraction Patterns

1989 ◽  
Vol 33 ◽  
pp. 409-416
Author(s):  
Katsumi Ohno ◽  
Hiroshi Harada ◽  
Toshihiro Yamagata ◽  
Michio Yamazaki
Keyword(s):  
Least Squares Method ◽  
Resolution Enhancement ◽  
Lattice Misfit ◽  
Window Function ◽  
Standard Reference Materials ◽  
X Ray Diffraction ◽  
X Ray ◽  
Numerical Resolution ◽  
Enhancement Method ◽  
Diffraction Patterns

AbstractA numerical resolution-enhancement method was developed for x-ray diffraction data measured with a conventional x-ray diffractometer. This method removes the instrumental broadening due to x-ray optics, including the spectral distribution of the x-ray source such as the CuKα doublet. The advantages of this method are to separate the cluster of peaks in x-ray powder patterns into individual peaks without previous knowledge of the number of peaks, and to remove CuKα2 reflection peaks automatically.The instrumental window function, which was approximated by a modified pseudo-Voigt function, was calculated from the measured diffraction pattern of NBS Standard Reference Materials (640B) by a non-linear least squares method. The simple diffraction patterns, including no CuKα2 peaks, were obtained from the diffraction patterns measured with the conventional x-ray diffractometer by using the window function mentioned above.The application of the method of determination of the lattice misfit between γ and γ phases in Ni-base superalloys was also described.

scholarly journals Design and Evaluation New Rice Planter Tool without Mechanical Engine for Improving Conventional Farmer's Posture as Revival of Agriculture's Indonesia

2013 ◽  
Vol 10 ◽  
pp. 116-121
Author(s):  
Amarria Dila Sari ◽  
Nurmala Pusfitasari ◽  
Riza Rahma
Keyword(s):  
Conventional Method ◽  
Injury Risk ◽  
Rice Field ◽  
Agricultural Sector ◽  
Comfort Level ◽  
Musculoskeletal Complaints ◽  
Musculoskeletal Discomfort ◽  
Long Duration ◽  
Rice Plantation ◽  
Work Method

Indonesia is an agricultural country and most of the population work in that sector. Indonesia focusses its development on the agricultural sector which emphasize on rice plantation. One of the obstacle on the agricultural sector in Indonesia is the conventional work method that is manually planting the rice in the rice field. However, this kind of method can affect the musculoskeletal system. Musculoskeletal discomfort complained because of excessive muscle contraction as an effect of heavy workload in a long duration. The objectives of this research was designing rice planter tool using participatory ergonomic approachment. This design could reduce the injury risks and musculoskeletal complaints and increase the productivity.There was a comparison between the proposed rice planter tool design with the conventional method of rice planting based on the musculoskeletal complaints, time efficiency and expended cost. TheREBA scoring result indicates that new-concept of rice planter tool improves subjective comfort level and reduces injury risks in the trunk, waist, right and left shoulders. By using the rice planter tool, the injury risk can be reduced until 66.67%. On the other side, suppose the same worker which usually plants one rice sprout with conventional method spends time about x seconds. Compared by using the proposed rice planter tool, the worker only spends 0,5x seconds from conventional method rice planting. Therefore, the time for rice planting will be more efficient by using this tool.

Effect of Large-Scale Wind Power Integration on Inter-Area Oscillation of Power System

2014 ◽  
Vol 672-674 ◽  
pp. 227-232
Author(s):  
Xu Zhi Luo ◽  
Hai Feng Li ◽  
Hua Dong Sun ◽  
An Si Wang ◽  
De Zhi Chen
Keyword(s):  
Power Systems ◽  
Power System ◽  
Wind Power ◽  
Large Scale ◽  
Oscillation Mode ◽  
Equivalent Model ◽  
Synchronous Generators ◽  
Actual System ◽  
Oscillation Modes ◽  
The Impact

With the fast development of the wind power, security constraints of power systems have become the bottleneck of the acceptable capacity for wind power. The underdamping oscillation modes of the inter-area is an important aspect of the constraints. In this paper, an equivalent model of a power system with wind plants has been established, and the impact of the integration of the large-scale wind power on the inter-area oscillation modes has been studied based on the frequency-domain and time-domain simulations. The results indicate that the damping of inter-area oscillation mode can be enhanced by the replacement of synchronous generators (SGs) with the wind generators. The enhancing degree is up to the participation value of the SGs replaced. The conclusion has been verified by the actual system example of Xinjiang-Northwest grid. It can provide a reference for system programming and operation.

Sign in / Sign up

Export Citation Format

Share Document