PEBB System Stability Margin Monitoring

2002 ◽  
Vol 8 (2) ◽  
pp. 261-276 ◽  
Author(s):  
Xiaogang Feng ◽  
Zhihong Ye ◽  
Fred C. Lee ◽  
Dushan Borojevic
Keyword(s):  
Stability Margin ◽  
System Stability ◽  
Linear Control ◽  
Small Signal ◽  
System A ◽  
Novel Approach ◽  
Implementation Approach ◽  
Dc Bus ◽  
Response Current ◽  
Measurement Approach

PEBB (power electronics building block) systems are typical nonlinear systems. Under the conventional but still popular linear control design, the system stability margin varies from one operating point to another. This paper introduces a novel approach to monitoring the DC bus stability margin of a PEBB system online. At the steady state of the system, a small-signal perturbation current î p is injected into the DC bus, and the load-side response current î L is measured. By checking the validation |î L ( jw)| < |î p ( jw)|, the system stability margin can be examined. Experiments on a 48 V DC DPS demonstrate the proposed measurement approach. An implementation approach is also proposed for an 800 V DC PEBB-based testbed system.

Novel Approach of Improving Secondary Electron Detector in FIB System

2018 ◽  
Author(s):  
Steve Wang ◽  
Jim McGinn ◽  
Peter Tvarozek ◽  
Amir Weiss
Keyword(s):  
Integrated Circuit ◽  
Secondary Electron ◽  
Focused Ion Beam ◽  
Ion Beam ◽  
Vital Role ◽  
Electron Detector ◽  
System A ◽  
Novel Approach

Abstract Secondary electron detector (SED) plays a vital role in a focused ion beam (FIB) system. A successful circuit edit requires a good effective detector. Novel approach is presented in this paper to improve the performance of such a detector, making circuit altering for the most advanced integrated circuit (IC) possible.

scholarly journals Application of Deep Reinforcement Learning to Predict Shaft Deformation Considering Hull Deformation of Medium-Sized Oil/Chemical Tanker

2021 ◽  
Vol 9 (7) ◽  
pp. 767
Author(s):  
Shin-Pyo Choi ◽  
Jae-Ung Lee ◽  
Jun-Bum Park
Keyword(s):  
Reinforcement Learning ◽  
Reaction Force ◽  
Measurement Data ◽  
System Stability ◽  
Main Bearing ◽  
Shaft System ◽  
Novel Approach ◽  
Design Changes ◽  
Prediction Techniques ◽  
Shaft Deformation

The enlargement of ships has increased the relative hull deformation owing to draft changes. Moreover, design changes such as an increased propeller diameter and pitch changes have occurred to compensate for the reduction in the engine revolution and consequent ship speed. In terms of propulsion shaft alignment, as the load of the stern tube support bearing increases, an uneven load distribution occurs between the shaft support bearings, leading to stern accidents. To prevent such accidents and to ensure shaft system stability, a shaft system design technique is required in which the shaft deformation resulting from the hull deformation is considered. Based on the measurement data of a medium-sized oil/chemical tanker, this study presents a novel approach to predicting the shaft deformation following stern hull deformation through inverse analysis using deep reinforcement learning, as opposed to traditional prediction techniques. The main bearing reaction force, which was difficult to reflect in previous studies, was predicted with high accuracy by comparing it with the measured value, and reasonable shaft deformation could be derived according to the hull deformation. The deep reinforcement learning technique in this study is expected to be expandable for predicting the dynamic behavior of the shaft of an operating vessel.

scholarly journals Verification of a control systems design for a series resonant converter based on a small-signal model

2021 ◽  
Author(s):  
Jermaine Stern
Keyword(s):  
Control System ◽  
Systems Design ◽  
Small Signal ◽  
Resonant Converter ◽  
Signal Model ◽  
System A ◽  
Small Signal Model ◽  
Series Resonant ◽  
Control Systems Design ◽  
Reference Input

The project verifies the performance of a control system designed for a Series Resonant Converter (SRC). A discrete small-signal model of an SRC was derived and used to design the control system. An accurate control system was designed in the frequency domain to eliminate the need for trail-and-error [sic] methods or other time domain methods. A PSPICE simulation of a regulated SRC circuit was used to test the control system. A prototype of the regulated SRC was developed to verify the simulated results. The tests performed demonstrated that the control system design provides a quick response. The tests determined that when a step input is applied to the reference input the control system adjusts the SRC's output voltage to the new reference input value. Also, the control system is able to regulate output load voltage in the presence of sudden load changes.

scholarly journals Grid-Forming Control Suitable for Large Power Transmission System Applications

2021 ◽  
Author(s):  
Taoufik QORIA ◽  
Xavier Guillaud
Keyword(s):  
Power Transmission ◽  
Stability Margin ◽  
Open Loop ◽  
System Stability ◽  
Test Cases ◽  
Large Power ◽  
Control Loops ◽  
Power Inverters ◽  
Practical Feasibility ◽  
Typical Solution

The inner cascaded structure-based grid-forming control is a typical solution used to impose an AC voltage magnitude across the output filters of the power inverters. Yet, because of the limited inverter’s bandwidth resulting from the low-switching frequencies in transmission systems, the interaction (i.e., coupling) between control loops is highly likely making the understanding of the system behavior complex and its simplification unaffordable and may also lead to instabilities. The novelty of this paper consists in proposing a simple open-loop direct voltage control to reduce the number of the inner control regulators, and thereby guaranteeing a decoupling between the inner and outer control layers as well as increasing the system stability margin. This statement is well supported with a small-signal analysis and progressive order model reduction of the system. The overall concept is validated in a 10-bus grid case while comparing the EMT and Phasor-based simulations. The practical feasibility of the control itself is experimentally proved with different test cases.

scholarly journals A Novel Approach for the Reimbursement of Permanent Partial Dental Disability Following Dental Injury

2015 ◽  
Vol 16 (6) ◽  
pp. 504-506
Author(s):  
Edgar Nehme ◽  
Sami Jad
Keyword(s):  
Quality Of Life ◽  
Insurance Companies ◽  
Court System ◽  
Permanent Disability ◽  
Dental Injury ◽  
System A ◽  
Novel Approach ◽  
New Formula

ABSTRACT Reimbursement of long-term permanent disability following a dental injury can lead to claims and legal involvement by the injured person. This will delay the treatment the patient's quality of life and the court system. A new formula has been hypothesized to address the problem. This might help the stakeholders including patients, insurance companies. The details of calculating the index and its significance are discussed. Implication studies are mandatory to refine the proposed hypothesis. How to cite this article Ayoub F, Nehme E, Jad S, Salameh Z. A Novel Approach for the Reimbursement of Permanent Partial Dental Disability Following Dental Injury. J Contemp Dent Pract 2015;16(6):504-506.

scholarly journals Improved Performance of DFIG-generators for Wind Turbines Variable-speed

2018 ◽  
Vol 9 (4) ◽  
pp. 1875
Author(s):  
Ihedrane Yasmine ◽  
El Bekkali Chakib ◽  
Bossoufi Badre
Keyword(s):  
Sliding Mode Control ◽  
Sliding Mode ◽  
System Stability ◽  
Control Technique ◽  
Induction Generator ◽  
Doubly Fed Induction Generator ◽  
Mode Control ◽  
Dc Bus ◽  
Doubly Fed ◽  
Grid Side

<span lang="EN-US">The following article presents the control of the power generated by the Doubly Fed Induction Generator, integrated into the wind system, whose rotor is linked to the power converters (Rotor Side Convert (RSC) and Grid Side Converter (GSC)) interfaced by the DC-BUS and connected to the grid via a filter (Rf, Lf) in order to obtain an optimal power to the grid and to ensure system stability. The objective of this study is to understand and to make the comparison between Sliding mode Control technique and the Flux Oriented Control in order to control the Doubly Fed Induction Generator powers exchanged with the grid, it also aims at maintaining the DC-BUS voltage constant and a unit power factor at the grid connection point.The results of simulation show the performance of the Sliding mode Control in terms of monitoring, and robustness with regard to the parametric variations, compared to the Flux Oriented Control. The performance of the systems was tested and compared with the use of MATLAB/Simulink software.</span>

scholarly journals Schizophrenia Increases Variability of the Central Antioxidant System: A Meta-Analysis of Variance From MRS Studies of Glutathione

2021 ◽  
Vol 12 ◽  
Author(s):  
Lena Palaniyappan ◽  
Priyadharshini Sabesan ◽  
Xuan Li ◽  
Qiang Luo
Keyword(s):  
Meta Analysis ◽  
Redox System ◽  
Antioxidant Response ◽  
Anterior Cingulate ◽  
System Stability ◽  
Careful Examination ◽  
Resonance Spectroscopy ◽  
1H Mrs ◽  
System A

Patients with schizophrenia diverge in their clinical trajectories. Such diverge outcomes may result from the resilience provided by antioxidant response system centered on glutathione (GSH). Proton Magnetic Resonance Spectroscopy (1H-MRS) has enabled the precise in vivo measurement of intracortical GSH; but individual studies report highly variable results even when GSH levels are measured from the same brain region. This inconsistency could be due to the presence of distinct subgroups of schizophrenia with varying GSH-levels. At present, we do not know if schizophrenia increases the interindividual variability of intracortical GSH relative to matched healthy individuals. We reviewed all 1H-MRS GSH studies in schizophrenia focused on the Anterior Cingulate Cortex published until August 2021. We estimated the relative variability of ACC GSH levels in patients compared to control groups using the variability ratio (VR) and coefficient of variation ratio (CVR). The presence of schizophrenia significantly increases the variability of intracortical GSH in the ACC (logVR = 0.12; 95% CI: 0.03–0.21; log CVR = 0.15; 95% CI = 0.06–0.23). Insofar as increased within-group variability (heterogeneity) could result from the existence of subtypes, our results call for a careful examination of intracortical GSH distribution in schizophrenia to seek redox-deficient and redox-sufficient subgroups. An increase in GSH variability among patients also indicate that the within-group predictability of adaptive response to oxidative stress may be lower in schizophrenia. Uncovering the origins of this illness-related reduction in the redox system stability may provide novel treatment targets in schizophrenia.

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