scholarly journals Comparison of Models of Single-Phase Diode Bridge Rectifiers for Their Use in Harmonic Studies with Many Devices

Energies ◽  
2021 ◽  
Vol 15 (1) ◽  
pp. 66
Author(s):  
Tatiano Busatto ◽  
Sarah K. Rönnberg ◽  
Math H. J. Bollen
Keyword(s):  
Numerical Simulation ◽  
Computational Complexity ◽  
Time Domain ◽  
Single Phase ◽  
Low Voltage ◽  
Level Of Detail ◽  
Trade Off ◽  
Current Harmonics ◽  
Voltage Distortion ◽  
Conduction Mode

Harmonic modeling of low-voltage networks with many devices requires simple but accurate models. This paper investigates the advantages and drawbacks of such models to predict the current harmonics created by single-phase full-bridge rectifiers. An overview is given of the methods, limiting the focus to harmonic analysis. The error of each method, compared to an accurate numerical simulation model, is quantified in frequency and time domain considering realistic input scenarios, including background voltage distortion and different system impedances. The results of the comparison are used to discuss the applicability of the models depending on the harmonic studies scale and the required level of detail. It is concluded that all models have their applicability, but also limitations. From the simplest and fastest model, which does not require a numerical solution, to the more accurate one that allows discontinuous conduction mode to be included, the trade-off involves accuracy and computational complexity.

scholarly journals Feasibility of Black-Box Time Domain Modeling of Single-Phase Photovoltaic Inverters Using Artificial Neural Networks

Energies ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 2118
Author(s):  
Elias Kaufhold ◽  
Simon Grandl ◽  
Jan Meyer ◽  
Peter Schegner
Keyword(s):  
Time Domain ◽  
Single Phase ◽  
Low Voltage ◽  
Black Box ◽  
Steady States ◽  
Domain Modeling ◽  
Dynamic Simulations ◽  
Time Domain Modeling ◽  
Artificial Neural ◽  
Grid Side

This paper introduces a new black-box approach for time domain modeling of commercially available single-phase photovoltaic (PV) inverters in low voltage networks. An artificial neural network is used as a nonlinear autoregressive exogenous model to represent the steady state behavior as well as dynamic changes of the PV inverter in the frequency range up to 2 kHz. The data for the training and the validation are generated by laboratory measurements of a commercially available inverter for low power applications, i.e., 4.6 kW. The state of the art modeling approaches are explained and the constraints are addressed. The appropriate set of data for training is proposed and the results show the suitability of the trained network as a black-box model in time domain. Such models are required, i.e., for dynamic simulations since they are able to represent the transition between two steady states, which is not possible with classical frequency-domain models (i.e., Norton models). The demonstrated results show that the trained model is able to represent the transition between two steady states and furthermore reflect the frequency coupling characteristic of the grid-side current.

MULTI UNITS OF SINGLE PHASE DISTRIBUTED GENERATION COMBINED WITH BATTERY ENERGY STORAGE FOR PHASE POWER BALANCING IN DISTRIBUTION NETWORK

2016 ◽  
Vol 78 (10-4) ◽  
Author(s):  
Amirullah Amirullah ◽  
Mochamad Ashari ◽  
Ontoseno Penangsan ◽  
Adi Soeprijanto
Keyword(s):  
Energy Storage ◽  
Single Phase ◽  
Low Voltage ◽  
Distribution Network ◽  
Battery Energy Storage ◽  
Current Harmonics ◽  
Line Current ◽  
Distributed Generators ◽  
Distribution Line ◽  
Battery Energy

Randomly installed distributed generators (DGs) in households may cause unbalanced line current in a distribution network. This research presents a battery energy system for balancing of line current in a distribution network involving multi units of single phase photovoltaic (PV) distributed generators (DGs). In this paper, the PV generators were simulated consisting of a buck-boost DC/DC converter and single phase DC/AC inverter. It was connected to the distribution line through the low voltage 220 volt 50 Hz. The proposed phase balancing system uses battery energy storage and three single phase bidirectional inverters. The inverter is capable of injecting current or absorbing power from the line to the battery. This inverter operation is arranged to balance each distribution line separately, as well as to improve other power quality parameters, such as voltage and current harmonics. Simulation results show that the system was capable of improving the unbalanced line current from 15.59 % to 11, 48 % and unbalanced line voltage from 1.76 % to 0.58 %. The system was able for increasing current harmonics from 0.98 % to 1.03% and voltage harmonics from 38.96% to 39.08%.

scholarly journals Fault Ride-Through Capability Enhancement for Microinverter Applications

2019 ◽  
Vol 2019 ◽  
pp. 1-12 ◽  
Author(s):  
Sajad Arab Ansari ◽  
Amir Reza Mizani ◽  
Siamak Ashouri ◽  
Javad Shokrollahi Moghani
Keyword(s):  
Power Systems ◽  
Single Phase ◽  
Low Voltage ◽  
Pv Systems ◽  
Low Voltage Ride Through ◽  
Fault Ride Through ◽  
Three Phase ◽  
Future Challenges ◽  
Wind Power Systems ◽  
Conduction Mode

Due to the fast growth of single-phase grid-connected photovoltaic (PV) systems, the existing grid codes are expected to be modified to guarantee the availability, quality, and reliability of the electrical system. Therefore, the future single-phase PV systems should become smarter and support low voltage ride-through (LVRT) capability, which are required for three-phase wind power systems. In this paper, the operation principle of a flyback inverter in a low-voltage ride-through operation is demonstrated in order to map future challenges. The steady state performance of the flyback inverter under voltage rise and drop conditions at boundary conduction mode (BCM) and discontinues conduction mode (DCM) is studied theoretically. The simulation results of the flyback inverter for various grid faults are presented to verify the theoretical analyses. The results indicate the fact that the flyback inverter at BCM condition can provide LVRT capability for photovoltaic microinverter applications in distributed generation (DG) systems, even though it does not need any auxiliary control branches and any limitations in components design.

A New Method for Faulted Line Identification in Neutral Non-Grounded Distribution Systems

2011 ◽  
Vol 383-390 ◽  
pp. 2496-2500
Author(s):  
Dan Li ◽  
Fang Zong Wang
Keyword(s):  
Numerical Simulation ◽  
Time Domain ◽  
Distribution Systems ◽  
Single Phase ◽  
Short Circuit ◽  
Difficult Problem ◽  
New Method ◽  
Vacuum Switch ◽  
Line Identification ◽  
Simulation Results

It is well-known that, the identification of the single-phase to ground faulted line in neutral non-grounded distribution systems is a difficult problem, due to its very small faulted current. This paper proposes a new method for the solution of this problem. The principle of the proposed method is to convert the neutral non-grounded system into a neutral grounded system temporarily by using a triggered vacuum switch based controllable short-circuit equipment. By time-domain numerical simulation, the proposed method is evaluated, and the simulation results have shown the effectiveness of the proposed method.

scholarly journals Multi-Point Time-Synchronized Waveform Recording for the Analysis of Wide-Area Harmonic Propagation

2020 ◽  
Vol 10 (11) ◽  
pp. 3869 ◽  
Author(s):  
Stanislav Babaev ◽  
Ravi Shankar Singh ◽  
Sjef Cobben ◽  
Vladimir Ćuk ◽  
Allan Downie
Keyword(s):  
Single Phase ◽  
Low Voltage ◽  
Harmonic Distortion ◽  
Distribution Networks ◽  
Harmonic Load ◽  
Medium Voltage ◽  
Voltage Distortion ◽  
Pv Inverter ◽  
Distributed Measurement ◽  
Selection Of

This paper focuses on studying the phenomenon of harmonic distortion propagation through distribution networks. This phenomenon is governed by a combination of factors involving the nature of harmonic loads and their dynamic interaction, the influence of background voltage distortion, and harmonic impedance values. The objective of the proposed research includes evaluation of the network response at different nodes to harmonic current injections via utilizing a time-synchronized distributed measurement system. The study is performed in a fully controlled and flexible test network with three medium voltage/low voltage (MV/LV) distribution substations and several managed LV harmonic sources, namely PV inverter, single-phase EV charger and emulated harmonic load with reference current injections. A selection of the results is analyzed and interpretation of the observed phenomena is given with implications that synchronized harmonic measurements can be considered as potential powerful instruments for analyzing power quality disturbances.

Measurements of single-phase and two-phase flows in a vertical pipe using ultrasonic pulse Doppler method and ultrasonic time-domain cross-correlation method

2013 ◽  
Vol 35 (3) ◽  
Author(s):  
Tat Thang Nguyen ◽  
Hiroshige Kikura ◽  
Ngoc Hai Duong ◽  
Hideki Murakawa ◽  
Nobuyoshi Tsuzuki
Keyword(s):  
Time Domain ◽  
Cross Correlation ◽  
Single Phase ◽  
Ultrasonic Pulse ◽  
Phase Flow ◽  
Beam Diameter ◽  
Vertical Pipe ◽  
Two Phase ◽  
Ultrasonic Time ◽  
Pulse Doppler

Ultrasonic Velocity Profile (UVP) method for measurement of single-phase and two-phase flow in a vertical pipe has recently been developed in the Laboratory for industrial and Environmental Fluid Dynamics, Institute of Mechanics, VAST. The signal processings of the UVP method include the ultrasonic pulse Doppler method (UDM)and the ultrasonic time-domain cross-correlation (UTDC) method. For two-phase flow, simultaneous measurements of both liquid and gas are enabled by using a multi-wave ultrasonic transducer (multi-wave TDX). The multi-wave TDX is able to emit and receive ultrasound of two different center frequencies of 2 MHz and 8 MHz at the same time and position. 2 MHz frequency with beam diameter 10 mm is exploited for measurement of gas. 8 MHz one with beam diameter 3 mm is used for liquid. Measurements have been carried out for laminar and turbulent single-phase flows and bubbly counter-current two-phase flows in two flow loops using two vertical pipes of 26 mm inner diameter (I.D.) and 50 mm I.D. respectively. Based on the measured results, assessment of each method is clarified. Applicability of each method for different conditions of pipe flow has been tested. Suggestions for application of the two methods have been recommended.

scholarly journals Measure of Similarity between GMMs by Embedding of the Parameter Space That Preserves KL Divergence

Mathematics ◽  
2021 ◽  
Vol 9 (9) ◽  
pp. 957
Author(s):  
Branislav Popović ◽  
Lenka Cepova ◽  
Robert Cep ◽  
Marko Janev ◽  
Lidija Krstanović
Keyword(s):  
Computational Complexity ◽  
Parameter Space ◽  
Recognition Accuracy ◽  
Gaussian Mixture Models ◽  
Gaussian Mixture ◽  
Dimensional Manifold ◽  
Dimensional Parameter ◽  
Trade Off ◽  
Measure Of Similarity ◽  
Lower Dimensional

In this work, we deliver a novel measure of similarity between Gaussian mixture models (GMMs) by neighborhood preserving embedding (NPE) of the parameter space, that projects components of GMMs, which by our assumption lie close to lower dimensional manifold. By doing so, we obtain a transformation from the original high-dimensional parameter space, into a much lower-dimensional resulting parameter space. Therefore, resolving the distance between two GMMs is reduced to (taking the account of the corresponding weights) calculating the distance between sets of lower-dimensional Euclidean vectors. Much better trade-off between the recognition accuracy and the computational complexity is achieved in comparison to measures utilizing distances between Gaussian components evaluated in the original parameter space. The proposed measure is much more efficient in machine learning tasks that operate on large data sets, as in such tasks, the required number of overall Gaussian components is always large. Artificial, as well as real-world experiments are conducted, showing much better trade-off between recognition accuracy and computational complexity of the proposed measure, in comparison to all baseline measures of similarity between GMMs tested in this paper.

Sign in / Sign up

Export Citation Format

Share Document