Assessment of harmonic distortion and voltage unbalance

2005 ◽  
Author(s):  
Z. Emin
Keyword(s):  
Harmonic Distortion ◽  
Voltage Unbalance

A New Islanding Detection Method Based on Wavelet-transform and ANN for Micro-grid Including Inverter Assisted Distributed Generator

2019 ◽  
Vol 20 (5) ◽  
Author(s):  
Zhengyuan Guan ◽  
Yuan Liao
Keyword(s):  
Wavelet Transform ◽  
Harmonic Distortion ◽  
Distribution Networks ◽  
Islanding Detection ◽  
Detection Zone ◽  
Distributed Generator ◽  
Voltage Unbalance ◽  
Typical Distribution ◽  
Artificial Neural Network Ann ◽  
Ann Classifier

Abstract This paper presents a new composite approach based on wavelet-transform and ANN for islanding detection of distributed generation (DG). The proposed method first uses wavelet-transform to detect the occurrence of events, and then uses artificial neural network (ANN) to classify islanding and non-islanding events. Total harmonic distortion and voltage unbalance are extracted as feature inputs for ANN classifier. The performance of the proposed method is tested by simulations for two typical distribution networks based on MATLAB/Simulink. The results show that the developed method can effectively detect islanding with low misclassification. The method has the advantages of small non-detection zone and robustness against noises.

Data-driven partition control strategy for harmonic distortion and voltage unbalance

2018 ◽  
Vol 12 (9) ◽  
pp. 2038-2045 ◽  
Author(s):  
Hao Yu ◽  
Qingquan Jia ◽  
Haidong Sun ◽  
Haiyan Dong
Keyword(s):  
Control Strategy ◽  
Harmonic Distortion ◽  
Data Driven ◽  
Voltage Unbalance

scholarly journals An Analysis of Voltage Quality in a Nanogrid during Islanded Operation

Energies ◽  
2019 ◽  
Vol 12 (4) ◽  
pp. 614 ◽  
Author(s):  
Jakob Nömm ◽  
Sarah Rönnberg ◽  
Math Bollen
Keyword(s):  
Short Circuit ◽  
Harmonic Distortion ◽  
Quality Data ◽  
Voltage Unbalance ◽  
Voltage Distortion ◽  
Voltage Quality ◽  
Islanded Operation ◽  
Harmonic Voltage ◽  
Even Harmonics

Voltage quality data has been collected in a single house nanogrid during 48 weeks of islanded operation and 54 weeks of grid-connected operation. The voltage quality data contains the voltage total harmonic distortion (THD), odd harmonics 3 to 11 and 15, even harmonics 4 to 8, voltage unbalance, short-term flicker severity (Pst) and long-term flicker severity (Plt) values, and voltage variations at timescales below 10 min. A comparison between islanded and grid-connected operation values was made, were some of the parameters were compared to relevant grid standard limits. It is shown that some parameters exceed the defined limits in the grid-standards during islanded operation. It was also found that the islanded operation has two modes of operation, one in which higher values of the short circuit impedance, individual harmonic impedance, harmonic voltage distortion and voltage unbalance were reached.

Voltage unbalance and harmonic distortion effects on induction motor power, torque and vibrations

2016 ◽  
Vol 140 ◽  
pp. 866-873 ◽  
Author(s):  
Pablo Donolo ◽  
Guillermo Bossio ◽  
Cristian De Angelo ◽  
Guillermo García ◽  
Marcos Donolo
Keyword(s):  
Induction Motor ◽  
Harmonic Distortion ◽  
Motor Power ◽  
Voltage Unbalance

Increasing Power Supply Efficiency for “Two Wire-Rail” Line Consumers

2020 ◽  
Vol 64 (188) ◽  
pp. 93-102
Author(s):  
Dmytro O. Bosyi ◽  
Denys R. Zemsky
Keyword(s):  
Power Quality ◽  
Power Supply ◽  
Harmonic Distortion ◽  
Voltage Unbalance ◽  
Phase Coordinates ◽  
Traction Network ◽  
Three Phase ◽  
Rail Line ◽  
Low Efficiency ◽  
Traction Power Supply

The article is devoted to the problem of non-traction consumers power supply of AC railways. The low efficiency of energy transfer is caused by the design of a non-traction power supply line. The absence of bilateral power is typical for non-traction network 27,5 kV which consist of “two wire-rail” lines. This line is outdated technology, which does not correspond to modern requirements on the power quality, but used on AC railways with three-phase traction transformers. The purpose of the article is to investigate the methods of power supply improvements for non-traction consumers in terms of voltage unbalance, harmonic distortions and energy losses. Connection of the phasing device to delta winding traction transformer for bilateral supplying non-traction customers from network 27,5 kV is suggested in the article. The implementation of a method to increase the efficiency of electricity transmission in the non-traction network power supply allows to reduce power losses from 720 MWh / year to 441 MWh / year, the voltage unbalance from 1,9% to 1,3% and the total harmonic distortion from 8 % to 6 % respectively. Additionally, investment attractiveness of the decision was evaluated. Keywords: non-traction customers, two wire-rail line, phase coordinates, AC railway, power quality

scholarly journals Control of Distributed Generators and Direct Harmonic Voltage Controlled Active Power Filters for Accurate Current Sharing and Power Quality Improvement in Islanded Microgrids

Inventions ◽  
2019 ◽  
Vol 4 (2) ◽  
pp. 27
Author(s):  
Hafiz Mudassir Munir ◽  
Rami Ghannam ◽  
Hong Li ◽  
Talha Younas ◽  
Noorbakhsh Amiri Golilarz ◽  
...  
Keyword(s):  
Power Quality ◽  
Hierarchical Control ◽  
Harmonic Distortion ◽  
Active Power Filter ◽  
Load Sharing ◽  
Active Power ◽  
Voltage Unbalance ◽  
Power Filter ◽  
Distributed Generators ◽  
Harmonic Voltage

Harmonics are regarded as one of the main challenges in a microgrid. This issue may even get worse when different distributed generators (DGs) work together to solve the load sharing problems due to mismatched feeder impedances and diversified DG ratings. Even though load sharing can be achieved, the microgrid suffers from voltage unbalance and total harmonic distortion (THD) issues at the output of DG terminals as well as at the point of common coupling (PCC). Thus, in this paper, the power quality improving method is discussed, with a target of load sharing under the hierarchical control of different DG units and an active power filter (APF) in microgrids. To achieve this objective, we propose integrating a direct harmonic voltage controlled APF with DGs to improve their harmonic compensation performance. This proposed control scheme has many advantages over conventional control using a shunt resistive active power filter (R-APF) with voltage controlled DGs. First, based on the existing THD level of the PCC voltage, the proposed scheme provides improved voltage compensation and reduction in THD in the islanded microgrid. Secondly, equal load sharing can be achieved simultaneously. Thus, the proposed scheme provides better performance and a seamless interface as the proposed study mainly contains both the voltage controlled DGs and the local based voltage detection APF.

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