Magazine Volume 3 Issue 1

Breakdown of Low Voltage electronic equipment in a 25 kV substation

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Conrad Bottu

The Belgian site being studied in this paper is connected to the public transmission grid (380 kV) by a High Voltage (HV) station. This HV station incorporates a 25 kV substation linked to a second substation via 25 kV underground cables. The second substation supplies the electric installations on the site.The substations contain 25 kV circuit breakers in interior type HV cells with a metallic casing (see pictures below). The insulation is realised by SF6 gas.

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Troubleshooting the logic selectivity system of network protection

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Didier Empain

In this new case study, a large plant in the transport sector was experiencing a general voltage interruption caused by a local short-circuit inside the plant’s electricity network. This happened because of a non-selective tripping of the general protections at the plant’s connection point. The company decided to take action to identify the origin of the malfunction and implement corrective measures. An electricity consultant was called in to investigate the case.

Power Quality for Healthcare Facilities

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Philip Keebler

The healthcare environment is made up of perhaps the most unusual combination of electronic loads found in any facility. Healthcare facilities not only rely upon commercial loads (such as computers, servers, and lighting system) and industrial loads (such as food preparation equipment, laundry equipment, medical gas systems, but also rely on electronic medical loads (that is, medical equipment to operate the facility and provide patient care services.

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Energy Efficiency in Industrial Processes: A case study of an automated pneumatic waste collection

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A new case study by: Andreas Sumper, Roberto Villafáfila, Rodrigo Ramírez and Paola Pezzini

Nowadays, energy is one of the most important prime materials in industrial processes. Highly automated industries need to have a reliable power supply and efficient energy utilisation in order to maintain both a high productivity and to be competitive. On the other hand, in industry automation, designing the automation process has an important influence on the later energy consumption.

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Flicker problems in a steel plant caused by Interharmonics

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A new case study by Michèle De Witte

A steel manufacturing plant was experiencing a flicker problem. Lights in the office areas of the plant were often flickering, affecting productivity and creating an irritating nuisance for employees. A Power Quality consultant was called in to investigate the case. He carried out measurements to gain a better understanding of the problem and to enable him to identify the source of the flicker phenomenon and the operating conditions in which it occurred.

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PFC units sizing in steel factory harmonics environment: a case study

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Angelo Baggini at al

The installation of non linear loads determines the presence of current and voltage harmonics and interharmonics. Components particularly sensitive to this kind of phenomena are power factor correction equipments. This paper describes the design process of a centralized PFC system under harmonic pollution conditions pointing out the key role of measurement campaigns.

Summary

This paper deals with PFC units' design related problems in case of installation in harmonics rich environments: in particular, the paper contains an overview of sizing approach used in a real case of PFC unit design for installation in a steel factory where new PFC units installation has been necessary after a fault with catastrophic consequences for the existing ones.

The document contains a report on stress calculation on PFC units due to harmonic currents generated by non linear loads installed in the above mentioned plant. Plant load, estimated to be around 80 MVA, is formed by a large number of small loads fed by power converters. This is a big disturbance source for the installation in terms of harmonic content.

In particular, due to the usual lack of real harmonics contents data availability, the main issue has been the process of definition of a generic harmonic distortion for installed loads, based on power converters installed and literature available data on power converters spectra and its on field verification for PFC optimal design, with three measurement campaigns aiming to verify real harmonic distortion and series and parallel resonance risk.

This kind of problem is very real, and, most of all, is constantly growing in other industries as well, not only in steel factories where harmonics content has always been a key problem.

Now, due to the continuous increase of power converter usage and equipment power consumption, and most of all to the increase of equipment disturbances sensitiveness, to avoid potentially tragic faults, a deep measurement campaign is the key solution at PFC units' design stage, also considering the usual lack of data on installation harmonic distortion.

The experience described in this paper constitutes the first detailed example of in-the-field verification of harmonic disturbance effects on two 8.4 Mvar, 13 kV PFC units in a harmonics critical environment aiming first of all at a detailed fault analysis (referred to pre-existent PFC Units) and then to a correct new unit design.

In the paper, the different design stages and related issues are described, including: installation network analysis, load analysis, harmonic distortion evaluation, PFC units stresses analysis, PFC units sizing, on field stresses verification.

This work highlights the strong need for deep measurement campaigns in harmonics rich industrial environment as the only way, in addition to a correct distortion pre-analysis aiming to a careful PFC design strategy to prevent potentially catastrophic faults

Impact of embedded generation on the voltage quality of distribution networks

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Giuseppe Esposito, Dario Zaninelli, George C. Lazaroiu, Nicolae Golovanov

The increasing concerns related to the global warming process determined the shifting towards the use of distributed generation (DG) designed to meet the environmental restrictions. The increasing penetration rate for the DG in the energy systems is raising technical and non technical problems that must be quickly solved in order to deeply exploit the opportunities and benefits offered by the DG technologies. In this paper, the analysis of the impact of distributed generation units on the voltage quality in a 6 kV medium voltage network is conducted.

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On Line Diagnostic Monitoring for Large Power Transformers

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Angelo Baggini, Franco Bua

In industrial plants, power transformers are expensive components of high strategic importance. Unavailability due to faults generally results in high costs, both in relation to repair work and in terms of lost production.Efficient diagnostic monitoring capable of highlighting incipient faults and therefore able to reduce the fault rate and downtime of the transformer within considered physiological limits are generally of extreme interest for maintenance departments.

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Energy Efficiency in Hospitals

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Rob van Heur

This Application Note describes the use of energy and the potential energy savings in the hospital sector, on the basis of theory and practical case studies. Hospitals represent some 6% of total energy consumption in the utility buildings sector, which includes offices, shops, hotels, restaurants, educational establishments and care institutions. The great majority of the energy used within a hospital is purchased from outside in the form of natural gas and electricity. A small proportion is bought in as diesel oil.

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EU poor power quality : an economic impact >€150bn

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Jonathan Manson presents the results of a survey conducted by the European Copper Institute (ECI) into the consequences for EU industry of poor power quality. These add up to >€150bn annually, are mainly experienced by industry and caused by power interruptions (dips, surges, transients and short interruptions). A call for action is made using the significant and disturbing conclusions drawn from the analysis of the survey.

 

http://leonardo-energy.com/eu-poor-power-quality-economic-impact-%E2%82%AC150bn

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