scholarly journals Harmonics in commercial building power systems

Author(s):  
Abdel H Charty

Harmonics are increasingly becoming a major source of power quality problems in today's commercial power distribution systems. Although they have been present in power distribution systems since the early days of AC power systems, their level has dramatically increased and the effect on power distributions has been more and more noticeable in the last decade. This dramatic increase of harmonic levels is mainly due to the introduction of non linear loads such as personal computers, servers, variable frequency drives and UPS systems. Harmonic problems are especially common in commercial buildings housing large computer rooms where the concentration of nonlinear loads per square foot is very high, and continue to grow higher as the footprint of network and communication equipment becomes smaller. This report will provide a deep look at harmonics in power distribution systems in commercial buildings, their sources and the different ways by which they can affect electrical systems and power quality. Some of the solutions commonly used to deal with the problem of harmonics are reviewed, and a critical analysis of their effectiveness is provided. Computer simulations using Matlab Simulink have been developed to illustrate key points when possible.

2021 ◽  
Author(s):  
Abdel H Charty

Harmonics are increasingly becoming a major source of power quality problems in today's commercial power distribution systems. Although they have been present in power distribution systems since the early days of AC power systems, their level has dramatically increased and the effect on power distributions has been more and more noticeable in the last decade. This dramatic increase of harmonic levels is mainly due to the introduction of non linear loads such as personal computers, servers, variable frequency drives and UPS systems. Harmonic problems are especially common in commercial buildings housing large computer rooms where the concentration of nonlinear loads per square foot is very high, and continue to grow higher as the footprint of network and communication equipment becomes smaller. This report will provide a deep look at harmonics in power distribution systems in commercial buildings, their sources and the different ways by which they can affect electrical systems and power quality. Some of the solutions commonly used to deal with the problem of harmonics are reviewed, and a critical analysis of their effectiveness is provided. Computer simulations using Matlab Simulink have been developed to illustrate key points when possible.


Author(s):  
M. Jawad Ghorbani ◽  
Hossein Mokhtari

This paper investigates the harmonic distortion and losses in power distribution systems due to the dramatic increase of nonlinear loads. This paper tries to determine the amount of the harmonics generated by nonlinear loads in residential, commercial and office loads in distribution feeders and estimates the energy losses due to these harmonics. Norton equivalent modeling technique has been used to model the nonlinear loads. The presented harmonic Norton equivalent models of the end user appliances are accurately obtained based on the experimental data taken from the laboratory measurements. A 20 kV/400V distribution feeder is simulated to analyze the impact of nonlinear loads on feeder harmonic distortion level and losses. The model follows a “bottom-up” approach, starting from end users appliances Norton equivalent model and then modeling residential, commercial and office loads. Two new indices are introduced by the authors to quantize the effect of each nonlinear appliance on the power quality of a distribution feeder and loads are ranked based on these new defined indices. The simulation results show that harmonic distortion in distribution systems can increase power losses up to 20%.


2012 ◽  
Vol 516-517 ◽  
pp. 1419-1424
Author(s):  
Wei Jun Yun ◽  
Gang Yao ◽  
Li Dan Zhou ◽  
Chen Chen ◽  
Jun Min Pan

Nonlinear loads generate a large amount of characteristic harmonics , deteriorate the power quality of power distribution systems in Advanced manufacturing enterprises. In this paper a novel hybrid active power filter is proposed which consists of a series thyristor switched filter (TSF) and small rated shunt active power filter(APF). TSF is tuned at fifth and seventh order harmonic frequencies. Consequently APF compensates for third and other order harmonics, unbalance current and reactive power. A new control method based on PHC strategy is presented for APF. The device has already got an application in one of the transformer substations of a automobile factory. It’s revealed that the proposed device can improve the power factor , reduce the harmonics injection and enhancement power quality of the power distribution systems.


2011 ◽  
Vol 354-355 ◽  
pp. 859-865
Author(s):  
Wei Jun Yun ◽  
Chen Chen ◽  
Jing Shuang Shen

Nonlinear loads are widely spread in automobile industry along with the development of power electronic technology, which causes proliferation of power quality problems, such as harmonics, voltage fluctuation, etc. The problems result in detrimental effects to the power distribution systems, increasing power loss in the network and affecting the safety operation of electrical appliances. This paper analyzed the power quality problems and proposed an enhancement scheme implemented in an automobile factory. The scheme has already got an application in one of the transformer substations. It’s revealed that the proposed scheme can improve significantly the power factor of the 400V bus in car body workshop, and the harmonics injection to the utility grid can be within the limit of related standard.


Mathematics ◽  
2018 ◽  
Vol 6 (9) ◽  
pp. 158
Author(s):  
Farzaneh Pourahmadi ◽  
Payman Dehghanian

Allocation of the power losses to distributed generators and consumers has been a challenging concern for decades in restructured power systems. This paper proposes a promising approach for loss allocation in power distribution systems based on a cooperative concept of game-theory, named Shapley Value allocation. The proposed solution is a generic approach, applicable to both radial and meshed distribution systems as well as those with high penetration of renewables and DG units. With several different methods for distribution system loss allocation, the suggested method has been shown to be a straight-forward and efficient criterion for performance comparisons. The suggested loss allocation approach is numerically investigated, the results of which are presented for two distribution systems and its performance is compared with those obtained by other methodologies.


2015 ◽  
Vol 16 (4) ◽  
pp. 357-384 ◽  
Author(s):  
Suresh Mikkili ◽  
Anup Kumar Panda

Abstract Electrical power quality has been an important and growing problem because of the proliferation of nonlinear loads such as power electronic converters in typical power distribution systems in recent years. Particularly, voltage harmonics and power distribution equipment problems result from current harmonics produced by nonlinear loads. The Electronic equipment like, computers, battery chargers, electronic ballasts, variable frequency drives, and switch mode power supplies, generate perilous harmonics and cause enormous economic loss every year. Problems caused by power quality have great adverse economic impact on the utilities and customers. Due to that both power suppliers and power consumers are concerned about the power quality problems and compensation techniques. Power quality has become more and more serious with each passing day. As a result active power filter gains much more attention due to excellent harmonic and reactive power compensation in two-wire (single phase), three-wire (three-phase without neutral), and four-wire (three-phase with neutral) ac power networks with nonlinear loads. However, this is still a technology under development, and many new contributions and new control topologies have been reported in the last few years. It is aimed at providing a broad perspective on the status of APF technology to the researchers and application engineers dealing with power quality issues.


Energies ◽  
2021 ◽  
Vol 15 (1) ◽  
pp. 199
Author(s):  
Chengwei Lei ◽  
Weisong Tian

Fused contactors and thermal magnetic circuit breakers are commonly applied protective devices in power distribution systems to protect the circuits when short-circuit faults occur. A power distribution system may contain various makes and models of protective devices, as a result, customizable simulation models for protective devices are demanded to effectively conduct system-level reliable analyses. To build the models, thermal energy-based data analysis methodologies are first applied to the protective devices’ physical properties, based on the manufacturer’s time/current data sheet. The models are further enhanced by integrating probability tools to simulate uncertainties in real-world application facts, for example, fortuity, variance, and failure rate. The customizable models are expected to aid the system-level reliability analysis, especially for the microgrid power systems.


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