Analysis on propagation characteristics of voltage sag through different types of transformers

Voltage sag caused by the faults in the power system has serious power quality issues and sometimes leads to interruption of power supply. The characteristics of voltage sag are its magnitude, time and phase angle jump (PAJ). This paper represents the estimation of phase angle jump (PAJ) when different types of faults are occurred in distribution system. Since the unbalancing is one of the major issues in distribution system that increases the zero sequence currents, over heats the distribution transformer, causes huge voltage drops in distributor etc. Therefore, the method used in this paper shows the PAJ when distributor is unbalance due to uneven loading or the line parameters of the distributor are unsymmetrical. Simple radial system is used to analyze the PAJ caused by the different types of faults and unbalancing. Different comparisons are made that are associated with PAJ such as PAJ vs fault impedance, zero sequence current and percentage of voltage unbalance. The research work is performed on MATLAB/SIMULINK to analyze the real time results.

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Cost of Industrial Process Shutdowns due to Voltage Sag and Short Interruption

Energies ◽

10.3390/en14102874 ◽

2021 ◽

Vol 14 (10) ◽

pp. 2874

Author(s):

Édison Massao Motoki ◽

José Maria de Carvalho Filho ◽

Paulo Márcio da Silveira ◽

Natanael Barbosa Pereira ◽

Paulo Vitor Grillo de Souza

Keyword(s):

Field Survey ◽

Industrial Process ◽

Sao Paulo ◽

Electricity Sector ◽

Voltage Sag ◽

International Literature ◽

Medium Voltage ◽

Specific Questionnaire ◽

Different Types ◽

The Cost

The objective of this work is to propose and apply a methodology to obtain the cost of industrial process shutdowns due to voltage sag and short interruption. A field survey, aided by a specific questionnaire, was carried out in several industries connected to medium voltage networks, in the states of Espírito Santo and São Paulo in Brazil. The results obtained were the costs per event and the costs per demand in a total of 33 companies in 12 different types of activities. It is noteworthy that this survey brings a relevant technical contribution to the electricity sector, helping to fill, even partially, an existing gap in both national and international literature.

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A Fast and Accurate Method for Power System Voltage Sag Detection

Iraqi Journal for Electrical And Electronic Engineering ◽

10.37917/ijeee.16.1.10 ◽

2020 ◽

Vol 16 (1) ◽

pp. 78-84

Author(s):

Adnan Diwan ◽

Khalid Abdulhassan ◽

Falih Alnahwi

Keyword(s):

Accurate Method ◽

Voltage Sag ◽

Dynamic Voltage Restorer ◽

Detection Techniques ◽

Voltage Restorer ◽

Detection Circuit ◽

Different Types ◽

Voltage Sag Detection ◽

Dynamic Voltage ◽

Speed And Accuracy

In order to mitigate the effect of voltage sag on sensitive loads, a dynamic voltage restorer (DVR) should be used for this purpose. The DVR should be accompanied with a fast and accurate sag detection circuit or algorithm to determine the sag information as quickly as possible with an acceptable precision. This paper presents the numerical matrix method as a distinctive candidate for voltage sag detection. The design steps of this method are demonstrated in detail in this work. The simulation results exhibit the superiority of this technique over the other detection techniques in term of the speed and accuracy of detection, simplicity in implementation, and the memory size. The results also accentuate the recognition capability of the proposed method in distinguishing different types of voltage sag by testing three different voltage sag scenarios.

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Vulnerability of Nuclear Power Plants to Voltage Sag Induced by Disturbances in the Transmission Grid: The Concept of Zone of Vulnerability for Voltage

Volume 2: Structural Integrity; Safety and Security; Advanced Applications of Nuclear Technology; Balance of Plant for Nuclear Applications ◽

10.1115/icone17-75177 ◽

2009 ◽

Author(s):

Nick Abi-Samra ◽

Alberto Del Rosso ◽

Frank Rahn

Keyword(s):

Nuclear Power ◽

Power Plants ◽

Nuclear Plant ◽

Voltage Sag ◽

Voltage Sags ◽

Diesel Generator ◽

Power Station ◽

Transmission Grid ◽

Nuclear Plants ◽

Different Types

Nuclear plants are particularly sensitive to events on the grid that may lead to undervoltage on the auxiliary or safety buses. Momentary voltage dips can cause separation from offsite power and operation of emergency diesel generator. Grid disturbances that occur in certain areas or “zones” in the surrounding network, may affect the operation of the nuclear plant, while disturbances from outside these zones may be cause no threat to the nuclear plant. A zone inside which a nuclear power station would be vulnerable to events on the surrounding grid can be defined as the Zone of Vulnerability (ZoV). Different types of ZoVs can be defined depending on the nature of the vulnerability being considered. This paper deals specifically with the Zone of Vulnerability associated with the risk of voltage sags in the safety and auxiliary for safety and auxiliary buses of nuclear plants induced by faults in the power grid. The paper first introduces the concept of ZoV_v and its importance for nuclear plants security. A methodology for determining the ZoV_v is then described.

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A New Zoning Method of Blasting Vibration Based on Energy Proportion and Its SVM Classification Models

Shock and Vibration ◽

10.1155/2021/6697682 ◽

2021 ◽

Vol 2021 ◽

pp. 1-13

Author(s):

Haixia Wei ◽

Jinfeng Chen ◽

Jie Zhu ◽

Xiaolin Yang ◽

Huaibao Chu ◽

...

Keyword(s):

High Frequency ◽

Kernel Functions ◽

Blasting Vibration ◽

Classification Models ◽

Propagation Characteristics ◽

Vibration Signals ◽

Svm Classification ◽

Different Types ◽

Different Characteristics ◽

Multiresolution Wavelet Analysis

The blasting vibration signals show obvious zoning propagation characteristics. Because of not considering the specific influences of geological and topographical conditions, the existing zoning methods of blasting vibration cannot fully describe the internal details of blasting vibration signals. Therefore, a new zoning method of blasting vibration based on energy proportion was proposed in this paper, in which the energy proportion in low, medium, and high frequency bands after multiresolution wavelet analysis is used as the zoning index to distinguish the different characteristics of blasting vibration signals in different zones. Based on the proposed zoning method, 343 sets of measured blasting vibration signals were used to train and test the SVM classification models with four different types of kernel functions. The testing results demonstrate that the zoning method of blasting vibration based on energy proportion has high feasibility, flexibility, and reliability, and the SVM classification models with RBF have higher accuracy than models with other kernel functions in blasting vibration zoning prediction.

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