Power Quality - studiecd.dk

1 Cahier technique no. 199 Power QualityPh. FerracciCollection Technique"Cahiers Techniques" is a collection of documents intended for engineersand technicians, people in the industry who are looking for more in-depthinformation in order to complement that given in product , these "Cahiers Techniques" are often considered as helpful"tools" for training provide knowledge on new technical and technological developmentsin the electrotechnical field and electronics. They also provide betterunderstanding of various phenomena observed in electrical installations,systems and "Cahier Technique" provides an in-depth study of a precise subject inthe fields of electrical networks, protection devices, monitoring and controland industrial automation latest publications can be downloaded from the schneider Electricinternet web : :The expert's placePlease contact your schneider electric representative if you want either a"Cahier Technique" or the list of available "Cahiers Techniques" collection is part of schneider electric s"Collection technique".

2 ForewordThe author disclaims all responsibility subsequent to incorrect use ofinformation or diagrams reproduced in this document, and cannot be heldresponsible for any errors or oversights, or for the consequences of usinginformation and diagrams contained in this of all or part of a "Cahier Technique" is authorised with theprior consent of the Scientific and Technical Division. The statement"Extracted from schneider electric "Cahier Technique" no.." (pleasespecify) is 199 Power QualityECT 199(e) october 2001 Philippe FERRACCIG raduated from the " cole Sup rieure d lectricit " in 1991, he wrotehis thesis on the resonant earthed neutral system in cooperation withEDF-Direction des Etudes et joined schneider electric in 1996, where he now conductsadvanced research into the area of electrotechnical and electricalpower Technique schneider electric no.

3 199 / Technique schneider electric no. 199 / QualityOne of the properties of electricity is that some of its characteristics dependnot only on the electricity producer/distributor but also on the equipmentmanufacturers and the customer. The large number of players combinedwith the use of terminology and definitions which may sometimes beimprecise partly explain why this subject area is so "Cahier Technique" aims to facilitate exchanges on this topic betweenspecialists and non-specialists, as well as customers, manufacturers,installers, designers and distributors. The clear terminology used shouldhelp avoid confusion. It describes the main phenomena causingdegradation in Power Quality (PQ), their origins, the consequences forequipment and the main solutions.

4 It offers a methodology for measuringthe PQ in accordance with differing aims. Illustrated with practicalexamples for the implementation of solutions, it shows that only byobserving best practice and by applying strict methodology (diagnostics,research, solutions, implementation and preventive maintenance) canusers obtain the right Quality of Power supply for their Objectives of Power Quality Degradation of PQ: origins - Voltage dips and Harmonics and Voltage variations and Effects of disturbance on Voltage dips and Voltage variations and Level of Power Evaluation EMC and planning Solutions for improving Voltage dips and Voltage Case Hybrid Real time reactive Protection against Technique schneider electric no.

5 199 / ContextThe widespread use of equipment which issensitive to voltage disturbance and/orgenerates disturbance itselfAs a consequence of their numerousadvantages (flexible operation, excellentefficiency, high performance levels, etc.), wehave seen the development and widespread useof automated systems and adjustable speeddrives in industry, information systems, and fluo-compact lighting in the service and domesticsectors. These types of equipment are bothsensitive to voltage disturbance and generatedisturbance multiple use within individual processesrequires an electrical Power supply which canprovide ever increasing performance in terms ofcontinuity and Quality . The temporary shutdown ofjust one element in the chain may interrupt thewhole production facilities (manufacture of semi-conductors, cement works, water treatment,materials handling, printing, steelworks,petrochemicals, etc.)

6 Or services (data processingcentres, banks, telecommunications, etc.).Consequently, the work of the IEC onelectromagnetic compatibility (EMC) has led tostricter and stricter standards andrecommendations (limitations on disturbancesemission levels, etc.).The opening up of the electricity marketThe rules governing the electricity sector areundergoing radical change: electricity productionhas opened up to competition, production isdecentralised, and (large) electricity consumersnow have the opportunity to choose their 1985, the Commission of the EuropeanCommunities states (directive 85/374) thatelectricity is to be considered a product and as aconsequence made it necessary to define itsessential characteristics addition, in the context of liberalising energymarkets, the search for competitiveness byelectricity companies now means that Quality hasbecome a differentiating factor.

7 A guarantee ofquality is a potential criterion of choice for industrialusers when looking for an energy Quality of electricity has become a strategic issuefor electricity companies, the operating, maintenanceand management personnel of service sectorand industrial sites, as well as for equipmentmanufacturers, for the following main reasons:c the economic necessity for businesses toincrease their competitiveness,c the widespread use of equipment which issensitive to voltage disturbance and/orgenerates disturbance itself,c the opening up of the electricity economic necessity for businessesto increase their competitivenessc Reduction of costs linked to loss of supplycontinuity and problems of non-qualityThe cost of disturbance (interruptions, voltage dips,harmonics, lightning overvoltages, etc.)

8 Is costs must take into account losses inproduction and raw materials, restarting ofproduction facilities, non- Quality of productionand delivery delays. The malfunction orshutdown of vital equipment such as computers,lighting and safety systems may put lives at risk( in hospitals, airport lighting systems, publicand high-rise buildings, etc.).Costs also include high Quality , targetedpreventive maintenance measures foranticipating possible problems. There is anincreasing transfer of responsibility from theindustrial user to the equipment manufacturer forthe provision of site maintenance; manufacturersare now becoming electricity Reduction of costs linked to oversizedinstallations and energy billsOther less obvious consequences of PQdegradation are:v A reduction of installation energy efficiency,leading to higher energy billsv Overloading of the installation, causingpremature ageing and increasing the risk ofbreakdown, leading in turn to oversizing ofdistribution equipmentThis is why professional users of electricity arekeen to optimise the operation of their Technique schneider electric no.

9 199 / Objectives of Power Quality measurementThe measurement parameters and accuracymay differ depending on the applicationWithin the context of a deregulated market,contractual relations may exist not onlybetween the electricity supplier and the enduser, but also between the Power productioncompany and transmission company or betweenthe transmission company and distributioncompany. A contractual arrangement requiresthat terms are defined jointly and mutuallyagreed upon by all parties. The parameters formeasuring Quality must therefore be definedand the values compared with predefined, arrangement frequently requires theprocessing of significant quantities of maintenanceEven where best practice is observed (single-line diagram, choice of protective devices andneutral point connection, application ofappropriate solutions) right from the designphase, malfunctions may occur duringoperation:c Disturbances may have been ignored The installation may have changed (newloads and/or modification).

10 Troubleshooting is generally required as aconsequence of problems of this aim is frequently to get results as quicklyas possible, which may lead to premature orunfounded measurement systems (for limitedperiods) or fixed apparatus (for continuousmonitoring) make it easier to carry outinstallation diagnostics (detection andarchiving of disturbances and triggering ofalarms).Optimising the operation of electricalinstallationsTo achieve productivity gains (operationaleconomies and/or reduction of operatingcosts) correct operation of processes andsound energy management are required, bothof which are factors dependent on , maintenance and managementpersonnel of service sector and industrial sitesall aim for a PQ which matches software tools to ensurecontrol-command and continuous monitoring ofthe installation are thus surveysSuch research requires a statistical approach onthe basis of wide-ranging results from surveysgenerally carried out by the operators oftransmission and distribution Power Benchmark the general performances of apower systemThese can be used, for example, to.