Harmonics ACostlyProblem EasilySolvedPB41M102

7/27/2019 Harmonics ACostlyProblem EasilySolvedPB41M102

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Harmonics a costly problemeasily solved

MAKING MODERN LIVING POSSIBLE

www.danoss.com/drives

5%Longer product life

All equipment exposed to5% lower voltage distortion

40%Reduction of harmonics

Prevent trips, equipment break-down and production stops


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Q

A

Q

A

Why areharmonics a problem?

Excessive harmonic distortion o the mains supplyimplies the presence o unacceptably large high

requency voltage components.

These components can not be utilized by electricalequipment and adverse efects can be severe and include:

Limitations on supply and network utilisation Increased losses Increased transormer, motor and cable heatingReduced equipment lie-timeCostly unintended production stopsDigital control system malunctions

Put simply, harmonics reduce reliability, afect productquality and increase operating costs.

What areharmonics?

An electrical AC supply is ideally apure sine-wave o either 50 or 60 Hz

undamental requency and allelectrical equipment is designed oroptimal perormance on this supply.

Harmonics are voltages and currents

which have requency components

that are integers multiple o the

undamental requency polluting

the pure sinusoidal waveorm.

Power electronics such as those usedin rectiers, variable speed drives,

UPS, lighting dimmer switches,televisions and hosts o otherequipment, draw current in anon-sinusoidal ashion.

This non-sine current interacts withthe mains supply and distorts thevoltage to a greater or lesser degreedepending upon the strength orweakness (ault level) o the supply.

Generally, the greater the amount oinstalled electronic power switchingequipment on-site, the greater thedegree o harmonic distortion.

Illustration o a pure sinusoidal waveorm being polluted.


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Danoss will, upon request, carry

out a ull harmonic survey and

recommend the most appropriate

and most cost-efective solution or

your site.

The survey will take the installedloads, the regulatory standards and

the diversity o your operation andapplication into consideration.

Diferent equipment exists to reduceharmonic pollution and they all havetheir advantages and disadvantages.

No single solution ofers a perectmatch or all applications andgrid conditions.

To achieve the optimum mitigationsolution, several parameters haveto be considered.

The key parameters can be dividedinto our groups:

Grid conditionsApplicationCompliance with standardsCost

QA

QA

Not at all.All Danoss VLT Drives comewith built-in DC-coils* to reduce

the harmonics intererence and

in most cases this is su cient to

avoid voltage pollution.

In some cases additional harmonicsuppression might be required dueto grid conditions or when multipledrives are installed.

For that purpose Danoss ofers awide range o mitigation solutionssuch as: VLT 12-pulse Drives andstandard drives with either built-in orexternal, active or passive harmoniclters.

In addition to this, Danoss also ofersboth passive and active solutionsor central harmonic suppressionwhere several loads can becompensated simultaneously.

Determining the degree o voltagepollution on your network is easilydone with the ree Danoss VLTMCT 31 Harmonic Calculationsotware.

It helps you determine whether ornot additional harmonic suppressionis needed.

Does that mean that everydrive leads to harmonic problems?

How is theoptimal harmonic solution chosen?

Danoss ofers on-site harmonic surveyand recommendation o the most suitablemitigation solution.

VLT MCT 31 estimates the harmonic currentand voltage distortion o your application anddetermines i harmonic ltering is needed.In addition the sotware can calculate the efect oadding mitigation equipment and i your systemcomplies with various standards.

*With exception o VLT Micro Drive FC 51 an external mitigation solution is available.


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The most important actor in determining the harmonic pollutiono a supply grid is the system impedance.

The system impedance is mostly dependent on the transormer sizein relation to the total power consumption o installed loads.The bigger the transormer is in relation to non-sinusoidal powerconsumption, the smaller the pollution.

The power grid is an interconnected system o power supplies andpower consumers all connected via transormers. All loads drawing

a non-sinusoidal current contribute to the pollution o the power grid not just at the low voltage supply but also at higher voltage levels.

When measuring at a power socket, some degree o pollution willthus always be present. This is reerred to as harmonic pre-distortion.As not all consumers draw three-phase current, the load on each phaseis dissimilar. This leads to unequal voltage values on each phase,causing phase imbalance.

Diferent harmonic solutions have diferent immunity againstpre-distortion and imbalance and so this has to be evaluated whendetermining the most suitable harmonic mitigation solution.

The essential considerations

Danoss solutions are easily installed, commissioned andndividually tuned or your application.

How do grid conditions

afect harmonics pollution?

Two VLT Advanced Active Filters or HVAC installed ata hospital to ensure a stable supply or vital equipment.

Two VLT Active Filters compensate ton vessel with limited wall space in a

>300 VLT Advanced Harmonic Filters installed at decentraloil pumping stations. Ensures 24hour/day pumping.


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Finally, the initial costs and runningexpenses have to be evaluated toensure that the most cost-efectivesolution is ound.

The initial cost o the diferentharmonic mitigation solutions incomparison to the drive varies withthe power range. The mitigation solu-tion that is most cost e cient or onepower range is not necessary bestcost t over the ull power range.

The running costs are determined bythe e ciency o the solutions acrossthe load prole and their lietimemaintenance/service costs.

Compared to active solutions, passivesolutions oten do not require regularmaintenance.On the other hand, active solutionstend to keep the true power-actorclose to unity over the entire loadrange, resulting in better energyutilization at partial load.

Also, uture development plans orthe plant or system need to be taken

into account because although onesolution will be optimal or a staticsystem, another will be more exiblei the system needs to be extended.

To ensure a certain grid quality,most power distribution companiesdemand that consumers comply withstandards and recommendations.

Diferent standards apply in diferentgeographical areas and industriesbut all o them have one basic goal, to limit the grid voltage distortion.

Standards depend on grid conditionsand so it is impossible to guaranteestandards compliance withoutknowing the grid specications.

Standards themselves do notcompel a specic mitigation solutionand so an understanding o standardsand recommendations is importantto avoid unnecessary cost ormitigation equipment.

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Harmonic distortion increases withthe amount o power consumed bythe non-linear load and so both thenumber o drives installed, and their

individual power sizes and loadproles, must be considered.

The distortion o a drive is denedby the total harmonic current distor-tion (THiD) which is the relation-ship between the sum o harmoniccomponents and the undamentalrequency.

The loading o each drive is importantbecause the THiD increases at partialload, thus over-sizing drives increasesthe harmonic pollution on the grid.

Additionally, environmental andphysical constraints must be takeninto account because the diferentsolutions all have characteristicsmaking them more or less suited tospecic conditions.

What needs to be considered is,or example, wall space, cooling air(polluted/contaminated), vibration,

ambient temperature, altitude,humidity, etc.

er drive applicationh environment.

Six cost optimized VLT 12-pulse drives incl. transormerinstalled at acility or material handling.

Three VLT Low Harmonic Drives installed at waste water stationensure compliance with IEEE519.

What applicationaspects mustbe considered?

What areas o cost must beconsidered when applyingharmonic mitigation?

Are compliancewith standardsconsistent globally?


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Grid conditionsBeore considering mitigation equipment,the system impedance has to be known.

No grid is ideal because pre-distortion and imbalanceis always present and so needs to be consideredwhen choosing equipment.

Application

A common pitall is over-sizing o componentsbetween load and grid. The consequence is a poorharmonic perormance, low system e ciency anda higher initial cost.

The route to ...

Gridconditions

Application

Compliancewithstandards

Cost

The initial cost o diferent mitigationequipment depends on power size.

The system e ciency determinesthe running expenses, but service costsalso need consideration.

Cost

Compliance with standards

A total voltage distortion o THvD = 5% is good engineeringpractice and will, in most cases, make the installation complywith local standards and recommendations. It ensures thatunintended tripping or component breakdown is not causedby harmonic pollution.


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Cost efective mitigation

Imbalance and pre-distortionThe harmonic mitigation peror-

mance o the diferent solutionsdepends on the grid quality.The higher the imbalance andpre-distortion, the more harmonicthe equipment has to suppress. Thegraph shows at what pre-distortionand imbalance level each techno-legy can keep its guaranteed THiDperormance.

Over-sizing

Published lter data are all given at100% loading but lters are seldomrun at ull load due to over-sizing andload prole.Serial mitigation equipment mustalways be sized or the maximumcurrent, but be aware o the durationo part load operation and evaluatethe diferent lter types accordingly.Over-sizing gives poor mitigationperormance and high running costs.It is also a waste o money.

Power size vs. initial costsCompared to the requencyconverter, the diferent solutionshave diferent add-on pricesdepending on power size.The passive solutions in generalofer the lowest initial cost and asthe complexity o the solutionsincrease, so does the price.

Standards complianceKeeping equipment immunityhigher than system distortion ensurestrouble ree operation.Most standards set restrictions ontotal voltage distortion according to aplanned level, oten between5% and 8%.Equipment immunity is, in mostcases, ar higher: or drives, between15-20%. However, this inuencesproduct lie adversely.

THiD(%)

Load (%)

Pre-distortion

0 200 400 600 800

20

60

100

140

Emission limitsindividualsources

Planninglevels

Immunitytest levels

Average Loading

6

55

80

12 18

LHD/AAFTHID 5%

AFETHID


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System impedanceAs an example, a 400 kW FC 102 drive

on a 1000 kVA transormer with5% impedance results in ~5% THvDtotal harmonic voltage distortion)t ideal grid conditions, whereas theame drive on a 1000 kVA, 8% imp.ransormer leads to 50% higher

THvD, namely 7.5%.

Harmonic perormance

Each harmonic mitigation technologyhas its own THiD characteristic whichs load dependent.

These characteristics are set at idealgrid conditions without pre-distortion

nd with balanced phases.Variations hereo will result in higherTHiD values.

Fullling the standardsTo determine whether or not the harmonicpollution o a given application/grid exceeds

specic standard, many complex calcula-ions must be done. With the help romree Danoss MCT 31 harmonic calculationotware, this is made easy and less timeonsuming.

System e ciencyThe running cost is mainly determinedby the overall system e ciency.This depends on the individual products,rue power-actors and e ciencies.

Active solutions tend to keep the true power-actor independent o load and grid varia-ions. On the other hand, active solutions areess e cient than passive solutions.

Total Harmonic distortionEach drive generates its own total

harmonic current distortion (THiD)which depends on the gridconditions. The bigger the drive isin relation to the transormer thesmaller the THiD.

Wall space

In many applications the amounto available wall space is limitedand must be utilized to the greatestextent possible.Based on diferent technologies, thevarious harmonic solutions eachhave their optimum size andpower relationship.

500

1000

1500

2000

2500

3000

132 315 630 kWVLT

AHF

12-pulse w/o autotransormer

LHD/AAF

5.5 30 90 315 630 1000 [kW]0

10

20

30

40

50

Drive power rating

THiD(%)

Width(mm)


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The applicationTo guarantee the many outdoor activities during thewinter season, multiple snow guns are ensuring snowavailability around the stadium at stersund in Sweden.

The snow guns can be quickly connected to a piping net-work where water is ed rom a single large waterpump located in a movable hut nearby.

As part o a renovation project, the customer requestedthat a new 200 kW water pump be installed.

The pump was to maintain constant water ow andpressure through the entire piping system independentlyo how many snow canons were connected.

Due to the long distance rom the power supply,the local authority imposed a maximum total currentdistortion o 5%.

The solutionA VLT Low Harmonic AQUA Drivewas installed to provide the requiredwater ow and pressure.

Load variations o 20-100% andexisting grid distortion o 2.4% wereimportant actors when theapplication was evaluated.

The drive was supplied with coatedPCBs and installed in IP 54 enclosuresto withstand the high humidity in theuninsulated galvanised pump shed.

Although the mains supply was weak,the drive easily met the < 5% THiDrequirement.

The application

In a world where the ocus on the reduction o CO2emissions is increasing, alternatives to ossil uels areincreasingly being sought. The bio-rening o cerealsmeans that grain (such as wheat) is broken downinto sugars and proteins and the sugars ermented intobio-uel. The protein solids and remaining parts o thegrain are converted into high protein animal ood leaving no waste.

To build one o Europes largest bio-reneries, thecustomer requested VLTs totalling more than 7 MW,ranging rom 2.2 350 kW.

With its own 3300/400 V transormer, the bio-reneryhad to set and comply with site harmonic standards toensure high reliability and the longest possible serviceintervals as demanded by the customer.To achieve this, harmonics were to be maintainedat less than 8% Total Demanded Distortion (TDD) atthe supply transormer.

The solution

In total 48 VLTs were installed tocontrol pumps and ventilation ansthroughout the bio-renery.

Based on the VLT power sizesand the demands or robustness/reliability, the majority o theVLTs were designed and installedwith Advanced Harmonic Filters

mounted side-by-side in IP 54 panelsand the specied 8% TDD was easilyachieved.

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... best match


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Environmentallyresponsible

VLT products are manuactured withrespect or the saety and well-being opeople and the environment.

All activities are planned and per-ormed taking into account the individ-ual employee, the work environmentand the external environment. Produc-tion takes place with a minimum onoise, smoke or other pollution andenvironmentally sae disposal o theproducts is pre-prepared.

UN Global CompactDanoss has signed the UN GlobalCompact on social and environmentalresponsibility and our companies actresponsibly towards local societies.

EU DirectivesAll actories are certied according toISO 14001 standard. All products ullthe EU Directives or General ProductSaety and the Machinery directive.Danoss VLT Drives is, in all productseries, implementing the EU Directiveconcerning Hazardous Substances inElectrical and Electrical Equipment(RoHS) and is designing all new prod-uct series according to the EU Direc-tive on Waste Electrical and Electronic

Equipment (WEEE).

Impact on energy savingsOne years energy savings rom our an-nual production o VLT drives will savethe energy equivalent to the energyproduction rom a major power plant.Better process control at the same timeimproves product quality and reduceswaste and wear on equipment.

What VLT is all aboutDanoss VLT Drives is the world leader among dedicated drives providers and still gaining market share.

Dedicated to drives

Dedication has been a key word since1968, when Danoss introduced theworlds rst mass produced variablespeed drive or AC motors and

named it VLT.

Twenty ve hundred employeesdevelop, manuacture, sell and servicedrives and sot starters in more thanone hundred countries, ocused onlyon drives and sot starters.

Intelligent and innovative

Developers at Danoss VLT Driveshave ully adopted modular principlesin development as well as design, pro-

duction and conguration.

Tomorrows eatures are developed inparallel using dedicated technologyplatorms. This allows the develop-ment o all elements to take place inparallel, at the same time reducingtime to market and ensuring thatcustomers always enjoy the benetso the latest eatures.

Rely on the experts

We take responsibility or everyelement o our products. The act thatwe develop and produce our owneatures, hardware, sotware, power

modules, printed circuit boards, andaccessories is your guarantee oreliable products.

Local backup globally

VLT motor controllers are operatingin applications all over the world andDanoss VLT Drives experts located inmore than 100 countries are ready tosupport our customers with applica-tion advice and service wherever theymay be.

Danoss VLT Drives experts dont stopuntil the customers drive challengesare solved.

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Harmonics ACostlyProblem EasilySolvedPB41M102