Current Harmonic Aggregation Cases for Contemporary Loads

Power electronic circuits in modern power supplies have improved the conversion efficiency on the one hand but have also increased harmonic emissions. Harmonic currents from the operation of these units affect the voltage waveforms of the network and could compromise the reliability of the network. Load and source non-linearity can, therefore, limit the renewable source’s hosting capacity in the grid, as a large number of inverter units may increase the harmonic distortions. As a result, voltage and current distortions could reach unbearable levels in devices connected to the network. Harmonic estimation modelling often relies on measurement data, and differences may appear in mathematical simulations as the harmonic aggregation or cancellation may generate different results due to the inaccuracies and limitations of the measurement device. In this paper, the effect of harmonic currents cancellation on the aggregation of different load currents is evaluated to show its impact in the network by presenting a comparison between the measurement and mathematical aggregation of harmonics. Furthermore, the harmonic cancellation phenomenon is also qualified for multiple loads connected to the power supply.

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A Fast Classification Method of Faults in Power Electronic Circuits Based on Support Vector Machines

Metrology and Measurement Systems ◽

10.1515/mms-2017-0056 ◽

2017 ◽

Vol 24 (4) ◽

pp. 701-720 ◽

Cited By ~ 2

Author(s):

Jiang Cui ◽

Ge Shi ◽

Chunying Gong

Keyword(s):

Classification Problem ◽

Classification Performance ◽

Classification Method ◽

Fault Classification ◽

Support Vector ◽

Power Electronic ◽

Electronic Circuits ◽

Power Electronic Circuits ◽

The One ◽

Fast Classification

AbstractFault detection and location are important and front-end tasks in assuring the reliability of power electronic circuits. In essence, both tasks can be considered as the classification problem. This paper presents a fast fault classification method for power electronic circuits by using the support vector machine (SVM) as a classifier and the wavelet transform as a feature extraction technique. Using one-against-rest SVM and one-against-one SVM are two general approaches to fault classification in power electronic circuits. However, these methods have a high computational complexity, therefore in this design we employ a directed acyclic graph (DAG) SVM to implement the fault classification. The DAG SVM is close to the one-against-one SVM regarding its classification performance, but it is much faster. Moreover, in the presented approach, the DAG SVM is improved by introducing the method of Knearest neighbours to reduce some computations, so that the classification time can be further reduced. A rectifier and an inverter are demonstrated to prove effectiveness of the presented design.

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Discontinuous Control and Stability Analysis of Step-Down DC-DC Voltage Converters

Engineering and Technology Journal ◽

10.30684/etj.v38i3a.567 ◽

2020 ◽

Vol 38 (3A) ◽

pp. 446-456

Author(s):

Bashar F. Midhat

Keyword(s):

Stability Analysis ◽

Lyapunov Stability ◽

Control Method ◽

Power Electronic ◽

Electronic Circuits ◽

Dc Voltage ◽

Power Electronic Circuits ◽

Lyapunov Stability Criterion ◽

Control Step ◽

Step Down

Step down DC-DC converters are power electronic circuits, which mainly used to convert voltage from a level to a lower level. In this paper, a discontinuous controller is proposed as a control method in order to control Step-Down DC-DC converters. A Lyapunov stability criterion is used to mathematically prove the ability of the proposed controller to give the desired voltage. Simulationsl1 are performedl1 in MATLABl1 software. The simulationl1 resultsl1 are presentedl1 for changesl1 in referencel1 voltagel1 and inputl1 voltagel1 as well as stepl1 loadl1 variations. The resultsl1 showl1 the goodl1 performancel1 of the proposedl1 discontinuousl1 controller.

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Numerical investigation on a melt-blowing die with internal stabilizers

Journal of Industrial Textiles ◽

10.1177/1528083719866935 ◽

2019 ◽

pp. 152808371986693 ◽

Cited By ~ 3

Author(s):

Changchun Ji ◽

Yudong Wang ◽

Yafeng Sun

Keyword(s):

Average Velocity ◽

Fiber Diameter ◽

Measurement Data ◽

Melt Blowing ◽

One Dimensional ◽

Temperature Decay ◽

Slot Die ◽

The Common ◽

The One ◽

Peak Value

In order to decrease the fiber diameter and reduce the energy consumption in the melt-blowing process, a new slot die with internal stabilizers was designed. Using computational fluid dynamics technology, the new slot die was investigated. In the numerical simulation, the calculation data were validated with the laboratory measurement data. This work shows that the new slot die could increase the average velocity on the centerline of the air-flow field by 6.9%, compared with the common slot die. Simultaneously, the new slot die could decrease the back-flow velocity and the rate of temperature decay in the region close to the die head. The new slot die could reduce the peak value of the turbulent kinetic energy and make the fiber movements more gradual. With the one-dimensional drawing model, it proves that the new slot die has more edge on the decrease of fiber diameter than the common slot die.

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