By Roman Targosz / Published on Thu, 2006-11-09 23:37
Application notes, reports, webcasts, presentations and minute lectures on high efficiency distribution transformers.
Read full story
By Isabelle Heriakian / Published on Thu, 2010-03-11 16:08
A prospective wind farm consisting of 21 turbines with 2 MW double-fed induction generators is planned to be connected to a 110 kV substation in distribution system.
In this case study, different network configurations are modelled.
The influence of the accuracy of grid modelling on grid harmonic impedance characteristic at a particular point is analysed, and a comparison of the results is done for the different network configurations.
Read full story
By Roman Targosz / Published on Wed, 2010-02-03 17:56
Leonardo ENERGY is launching a comprehensive e-learning multi-course on Power Quality.
The list of courses:
Read full story
By Roman Targosz / Published on Tue, 2010-02-02 17:21
The second course in the comprehensive programme on power quality covers the subject of harmonics and interharmonics.
The knowledge acquired during the course should be sufficient for:
Read full story
By Isabelle Heriakian / Published on Tue, 2009-08-04 09:03
Industrial facilities are source of major disturbances to power system due to more and more large power loads being installed that, apart of their good functional properties, are characterised by negative impact on the quality of power.
The adverse impact of non-linear loads on a power system can be mitigated by means of compensation equipment like fixed capacitor (FC), thyristor controlled reactor (TCR) - FC/TCR.
The purpose of FC/TCR compensator is compensation of the fundamental component reactive power and filtering selected current harmonics.
Read full story
By HDK / Published on Wed, 2009-05-27 07:57
A hybrid parallel active filter / off-line uninterruptible power supply (UPS) system is proposed here. The hybrid system contains a single inverter, which acts as a parallel active filter during the normal mode of operation (when the AC supply is available) and also supplies the load with energy from the UPS back-up battery during the back-up mode of operation (when the AC supply is not available, or is beyond the preset tolerance). In both modes of operation, the inverter is controlled in such a way that the line current is a pure sinusoid.
Read full story
By HDK / Published on Wed, 2009-05-27 07:34
This brief communication addresses the case of a dc nonlinear load supplied with a perfectly constant instantaneous power. A careful analysis shows that this condition does not provide optimum transfer of electric energy.
Read full story
By Isabelle Heriakian / Published on Mon, 2009-05-11 09:17
A theatre encountered a situation where incorrect operation of the earth fault protection system of a back-up generator tripped the circuit breaker unexpectedly when dimmer loads were fully used.
The generator was used to supply critical loads via an automatic transfer switch (ATS) and the problem was caused by high levels of third harmonic current produced by dimmers and an inappropriate installation of neutral and ground system.
Read full story
By Jonathan Manson / Published on Mon, 2009-01-12 16:45
By Jonathan Manson and Roman Targosz
Since the end of the 1990s the European Copper Institute [ECI] has been concerned about the impact experienced by commerce and industry of the changing nature of the energy demands organisations face as a result of equipment technological advances, the increasing need o build in resilience into their electrical power installations and the presumed mounting costs of not taking either adequate preventative or reactive action to accommodate the changes.
After some preliminary small scale studies into the impact of poor power quality on such organisations and as the empirical but anecdotal evidence mounted being discussed at length among the growing membership of the Leonardo Power Quality Initiative [LPQI*], so ECI decided to mount an extensive research project into what the impacts were on key energy suing industrial sectors of their not coping with poor power quality.
The project itself took over two years to complete and its results have been exposed in 2007 to a broad technical academic community with a view to securing their support and agreement for this work, the findings of which, whilst not surprising to us, make very negative reading in terms of the avoidable wastage and economic losses incurred by these industrial sectors at a time when energy and resource efficiency are the demands of today. Apply this to more commercial interpretation and it is clear that the EU’s competitive position is also unnecessarily undermined asa a result of this wastage.
This report presents the European PQ Survey – it is clear that the industrial sectors interviewed annually lose upwards of €150 billion as a direct result of their electrical power installations not being sufficiently reliable and resilient for today’s and future operating demands.
The causes of these losses are not new nor are the Power Quality [PQ] phenomena involved. What was both surprising as well as concerning was and we suspect is still the relative lack of analysis and measurement that take place among these power critical industries to be able to know what is causing these damaging interruptions to their operations.
Read full story
By Bryony Samuel / Published on Wed, 2008-12-03 14:20
The presence of harmonic voltages and currents in the supply network cause many common power quality (PQ) problems.
Read full story
By jan.desmet@howest.be / Published on Wed, 2008-12-03 14:14
This Application Note discusses the effects of harmonic currents on power transformers. The main consequence is an increase in losses, mainly in the windings. Higher losses mean that more heat is generated in the transformer so that the operating temperature increases, leading to deterioration of the insulation and a potential reduction in lifetime. As a result, it is necessary to reduce the maximum power load on the transformer, a practice referred to as de-rating, or to take extra care in the design of the transformer to reduce these losses.
Read full story
By Bryony Samuel / Published on Wed, 2008-12-03 14:12
This Application Note discusses the sizing of neutral conductors in the presence of ‘triple-N’ harmonics– that is, currents with a harmonic order that is a multiple of three. This issue is particularly important in low voltage systems where harmonic pollution by single phase loads is an increasingly serious problem. Triple-N harmonic currents add arithmetically with the result that neutral currents that are often significantly higher than the phase currents.
Read full story
By Bryony Samuel / Published on Wed, 2008-12-03 14:10
This application note discusses the compatibility, with respect to harmonic voltage levels, of load devices with the electricity supply system. Consumers' equipment operating on the network causes disturbances which affect the proper operation of other equipment on the network.
To ensure compatibility it is necessary both to control the maximum level of disturbance that may be present at any point on the network and to establish a level of disturbance to which every item of equipment will be immune.
Read full story
By Bryony Samuel / Published on Wed, 2008-12-03 12:52
This Application Note discusses the use of active filters to reduce harmonic currents in installations. Active filters work by providing the harmonic current required by the load instead of it being drawn from the supply.
Read full story
By Bryony Samuel / Published on Wed, 2008-12-03 12:44
Capacitor banks have been used for many years to compensate fundamental reactive power required by resistive-inductive loads. However, non-linear loads are now becoming predominant and capacitor banks now have to be designed to withstand excess harmonic current and to avoid the risk of resonance with inductances in close (electrical) proximity.
Read full story
By Hans De Keulenaer / Published on Wed, 2008-11-05 12:20
Miroslaw Wciœlik, Robert Kazala, Michal Kaskawski, Tomasz Kwaœniewski
The monitoring system of power quality in a network is introduced. The paper deals with functionality, hardware and software of the system. Algorithms of data processing as well as ways of improving processing accuracy of signal processor are presented. Sample results observed by means of the developed system are shown.
Read full story
By Hans De Keulenaer / Published on Mon, 2008-09-22 10:00
The paper deals with the general analysis of one part of the electromagnetic compatibility (EMC ) problem — the electromagnetic coupling applied in the field of power electrical systems as. The simulation analyses and practical measurements of the electromagnetic coupling are presented in part II . Obtained results confirm the correctness of the theoretical analyses and so they can be used for predictive stating of EMC quality of individual new electrotechnical products.
Read full story
By Hans De Keulenaer / Published on Mon, 2008-09-15 16:43
Sensitive equipment and non-linear loads are now more common in both the industrial/commercial sectors and the domestic environment. Because of this a heightened awareness of power quality is developing amongst electricity users. Therefore, power quality is an issue that is becoming increasingly important to electricity consumers at all levels of usage. This article presents the fuzzy system to determine the power quality. The performance of three-phase induction motor is observed for different power quality conditions in laboratory.
Read full story
