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.

scholarly journals Effect of the Harmonic Voltage Distortion on the Efficiency of a Compact Fluorescent Lamp

2020 ◽  
Vol 29 (54) ◽  
pp. e11604
Author(s):  
Esteban Rojas-Osorio ◽  
Andrés Julián Saavedra-Montes ◽  
Carlos Andrés Ramos-Paja
Keyword(s):  
Mathematical Model ◽  
Test Bench ◽  
Harmonic Distortion ◽  
Fluorescent Lamp ◽  
Constant Frequency ◽  
Voltage Distortion ◽  
Variable Voltage ◽  
Harmonic Voltage ◽  
Compact Fluorescent Lamp ◽  
Harmonic Components

This paper evaluates the effect of the voltage harmonic distortion over the efficiency of a compact fluorescent lamp that is fed with a constant RMS voltage and constant frequency. Several works have been published about the assessment of compact fluorescent lamps, but the effect of the voltage distortion over the efficiency is still an open topic. This work focuses on designing an experiment to estimate the efficiency of a compact fluorescent lamp while changing the voltage harmonic distortion of the power supply. First, a mathematical model that represents a bus susceptible to harmonic distortion (high impedance) that feeds the compact fluorescent lamp is analyzed. Then the mathematical model is reproduced through a test bench in a laboratory of rotating electrical machines. The test bench produces a three-phase bus with constant voltage and frequency, and variable voltage harmonic distortion. The compact fluorescent lamp is subjected to varying harmonic voltage distortion while recording its electrical variables and the produced lumens to estimate its efficiency. That is a practical approach to calculate the lamp efficiency while several works limit their scope measuring only the efficiency of the input converter. The experimental results show that a variation of the voltage harmonic distortion of 8 % on a compact fluorescent lamp reduces its efficiency. Those results put into evidence the importance of regulating harmonic distortion limits to reduce or prevent the increment of power losses caused by harmonic components.

Analysis of Risk Factors for Harmonic Voltage Distortion Caused by Inrush Current

2014 ◽  
Vol 521 ◽  
pp. 217-221
Author(s):  
Yu Fei Teng ◽  
Fan Tang ◽  
Wei Wei ◽  
Li Jie Ding ◽  
Hua Zhang
Keyword(s):  
Risk Factors ◽  
Harmonic Distortion ◽  
Power Grids ◽  
Inrush Current ◽  
Long Distance ◽  
Simulation Research ◽  
Voltage Distortion ◽  
Light Load ◽  
Connection Line ◽  
Harmonic Voltage

With the power grids gradually extending to remote areas, the number of the connection line with long distance, light load are increasing. In such a grid, the closing operation of the unloaded transformer may cause severe voltage distortion in the end of system due to the inrush current. This paper analyzes the risk factors for harmonic voltage distortion caused by the inrush current with two methods, including indexes comparison and simulation research. It is showed that the different generators operation modes and load levels have major impact on the risk for voltage harmonic distortion caused by inrush current in the system, and these factors need to be carefully considered in the analysis.

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.

Harmonic Voltage Distortion Damping Method for Parallel-Connected LCL-Type Inverters in Islanded Operation

2019 ◽  
Vol 66 (11) ◽  
pp. 9032-9044 ◽  
Author(s):  
Leming Zhou ◽  
Wenhua Wu ◽  
Yandong Chen ◽  
Jie Jiang ◽  
Xiaoping Zhou ◽  
...  
Keyword(s):  
Voltage Distortion ◽  
Islanded Operation ◽  
Harmonic Voltage

scholarly journals RAILWAY SYSTEM IMPACT ON VOLTAGE QUALITY AT THE LEVEL OF THE CROATIAN TRANSMISSION NETWORK

2020 ◽  
Vol 69 (2) ◽  
pp. 19-23
Author(s):  
Denisa Galzina ◽  
Eraldo Banovac ◽  
Tomislav Tomiša
Keyword(s):  
Harmonic Distortion ◽  
Quality Measurement ◽  
Theoretical Description ◽  
Transmission Network ◽  
Two Phase ◽  
Voltage Unbalance ◽  
Railway Systems ◽  
Voltage Quality ◽  
Railway System ◽  
The Impact

Railway systems are single-phase loads, connected to two-phase of the three-phase supply network. Therefore, they negatively affect the voltage quality, primarily the voltage unbalance. In addition to voltage unbalance, railway systems inject current harmonics into the network due to controllable diode or thyristor drives used to operate the train. The paper gives a short theoretical description of the harmonic distortion and the voltage unbalance as well as the results of the voltage quality measurement. Moreover, the paper shows the impact of the railway system on the transmission network in the case that the facilities are connected to the 110 kV voltage level.

scholarly journals The Diamond League athletic series: does the air quality sparkle?

2021 ◽  
Author(s):  
James R. Hodgson ◽  
Lee Chapman ◽  
Francis D. Pope
Keyword(s):  
Particulate Matter ◽  
Air Quality ◽  
Performance Metrics ◽  
Urban Air Pollution ◽  
Quality Data ◽  
Performance Variation ◽  
Short And Long Term ◽  
Respiratory Conditions ◽  
Race Performance

AbstractUrban air pollution can have negative short- and long-term impacts on health, including cardiovascular, neurological, immune system and developmental damage. The irritant qualities of pollutants such as ozone (O3), nitrogen dioxide (NO2) and particulate matter (PM) can cause respiratory and cardiovascular distress, which can be heightened during physical activity and particularly so for those with respiratory conditions such as asthma. Previously, research has only examined marathon run outcomes or running under laboratory settings. This study focuses on elite 5-km athletes performing in international events at nine locations. Local meteorological and air quality data are used in conjunction with race performance metrics from the Diamond League Athletics series to determine the extent to which elite competitors are influenced during maximal sustained efforts in real-world conditions. The findings from this study suggest that local meteorological variables (temperature, wind speed and relative humidity) and air quality (ozone and particulate matter) have an impact on athletic performance. Variation between finishing times at different race locations can also be explained by the local meteorology and air quality conditions seen during races.

scholarly journals Combined Correlation and Cluster Analysis for Long-Term Power Quality Data from Virtual Power Plant

Electronics ◽  
2021 ◽  
Vol 10 (6) ◽  
pp. 641
Author(s):  
Michał Jasiński
Keyword(s):  
Cluster Analysis ◽  
Power Plant ◽  
Power Quality ◽  
Quality Data ◽  
Virtual Power ◽  
Distributed Resources ◽  
Virtual Power Plant ◽  
And Cluster Analysis ◽  
Global Indicators

Analysis of the connection between different units that operate in the same area assures always interesting results. During this investigation, the concerned area was a virtual power plant (VPP) that operates in Poland. The main distributed resources included in the VPP are a 1.25 MW hydropower plant and an associated 0.5 MW energy storage system. The mentioned VPP was a source of synchronic, long-term, multipoint power quality (PQ) data. Then, for five related measurement points, the conclusion about the relation in point of PQ was performed using correlation analysis, the global index approach, and cluster analysis. Global indicators were applied in place of PQ parameters to reduce the amount of analyzed data and to check the correlation between phase values. For such a big dataset, the occurrence of outliers is certain, and outliers may affect the correlation results. Thus, to find and exclude them, cluster analysis (k-means algorithm, Chebyshev distance) was applied. Finally, the correlation between PQ global indicators of different measurement points was performed. It assured general information about VPP units’ relation in point of PQ. Under the investigation, both Pearson’s and Spearman’s rank correlation coefficients were considered.

scholarly journals Modeling Building Stock Development

2021 ◽  
Vol 13 (2) ◽  
pp. 723
Author(s):  
Antti Kurvinen ◽  
Arto Saari ◽  
Juhani Heljo ◽  
Eero Nippala
Keyword(s):  
Model Development ◽  
Housing Demand ◽  
Quality Data ◽  
Building Stock ◽  
Test Arena ◽  
Climate Targets ◽  
Wide Range ◽  
Key Variables ◽  
The Impact

It is widely agreed that dynamics of building stocks are relatively poorly known even if it is recognized to be an important research topic. Better understanding of building stock dynamics and future development is crucial, e.g., for sustainable management of the built environment as various analyses require long-term projections of building stock development. Recognizing the uncertainty in relation to long-term modeling, we propose a transparent calculation-based QuantiSTOCK model for modeling building stock development. Our approach not only provides a tangible tool for understanding development when selected assumptions are valid but also, most importantly, allows for studying the sensitivity of results to alternative developments of the key variables. Therefore, this relatively simple modeling approach provides fruitful grounds for understanding the impact of different key variables, which is needed to facilitate meaningful debate on different housing, land use, and environment-related policies. The QuantiSTOCK model may be extended in numerous ways and lays the groundwork for modeling the future developments of building stocks. The presented model may be used in a wide range of analyses ranging from assessing housing demand at the regional level to providing input for defining sustainable pathways towards climate targets. Due to the availability of high-quality data, the Finnish building stock provided a great test arena for the model development.

scholarly journals Analyzing Individual-Level Secondary Data with Instrumental Variable Methods Is Useful for Studying the Effects of Air Pollution on Dementia

2021 ◽  
Vol 79 (1) ◽  
pp. 15-23
Author(s):  
Kelly C. Bishop ◽  
Sehba Husain-Krautter ◽  
Jonathan D. Ketcham ◽  
Nicolai V. Kuminoff ◽  
Corbett Schimming
Keyword(s):  
Air Pollution ◽  
Instrumental Variable ◽  
Secondary Data ◽  
Quality Data ◽  
Long Term Effects ◽  
Individual Level ◽  
Medicare Claims Data ◽  
Advance Knowledge ◽  
Air Quality Data

We hypothesize that analyzing individual-level secondary data with instrumental variable (IV) methods can advance knowledge of the long-term effects of air pollution on dementia. We discuss issues in measurement using secondary data and how IV estimation can overcome biases due to measurement error and unmeasured variables. We link air-quality data from the Environmental Protection Agency’s monitors with Medicare claims data to illustrate the use of secondary data to document associations. Additionally, we describe results from a previous study that uses an IV for pollution and finds that PM2.5’s effects on dementia are larger than non-causal associations.

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