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IEEE Standard 519-1992 Application in Industrial Power Distribution

Networks with a New Monitoring Approach

JOO PEDRO TROVO (1) PAULO PEREIRINHA (1,2) HUMBERTO JORGE (3,4)(1)DEE-ISEC, Engineering Institute of Coimbra, Rua Pedro Nunes, P-3030-199 COIMBRA, PORTUGAL

(2)CASE, Bera Interor University, Calada Fonte do Lamero, 6201-001 COVILH, PORTUGAL(3)DEEC, University of Coimbra, Plo II, P-3030-290 COIMBRA, PORTUGAL

(4)INESC - Coimbra, Rua Antero Quental 199, P-3000-030 COIMBRA, [email protected], [email protected], [email protected]

Abstract: - This article presents a new concept of application for the IEEE Standard 519-1992 in industrial en-vironments achieved through the spreading of networked remote acquisition systems. This new monitoring ap-

proach concept for the IEEE Standard application, inside the industrial power distribution, has the capability toremotely study the propagation of harmonic disturbances, to determine the waveform distortion caused by har-monic sources, to quantify the impact of these disturbances and to elaborate quality indexes reports based onrecent harmonics analysis techniques. It is presented experimental results made in a real industrial plant, prov-

ing the system viability and value added in this problematic area.

Key-Words: -Harmonic Distortion, Harmonic Analysis, Power Quality, Industrial Plants, Power System Moni-toring, Harmonic Standards.

1 IntroductionIn the past few years, the power supply network in-side the industrial plants, herein called IndustrialPower Distributions (IPD), has been perturbed byharmonics pollution, generated by equipments in-side the plant installation or resulting from a

neighbourhood installation. This problem can pre-sent harmful effects, with different consequencesdepending on the application domain.

The liberalization of the electric energy market,costs reduction policies and the proliferation of sen-sitive equipment with regard to voltage disturbances(in its majority also source of disturbances) [1] re-quire well defined rules in order to keep the PowerQuality (PQ) of the energy supplied to industrialnetworks. In this context, monitor systems allow thecontrol of normative rates and the study of the best

place for the most sensitive and/or disturbingequipment in the facilities [3].

The harmonic distortion of voltage and/or currentwaveform corresponds to a specific case in the PQ

problematic issues. In power networks that havecurrent and voltage harmonic sources (arc furnaces,static power converters, illumination, etc.) exceed-ing the permissible limits [3-5] there is the need tocorrect this distortion.

Typically, the standard limits are applied to indi-vidual loads. Nevertheless, monitoring all the loadsis a strong challenge, from the point of view of the

measurement equipment technology and, obviously,of its associated costs. Also, as the distortion levels

defined by the norms can be quickly exceed, atsome points inside the customer facility, whenheavy pollutant loads are present, it can lead to un-necessary worries because the basic functions ofthese loads are not directly affected.

On the other hand, the existence of high distor-

tion next to specific loads does not necessarily resultin out-of-limit distortion in the interconnection be-tween the electrical distribution system and the plantinstallation [2]. According to this fact, some stan-dards specify that the PQ only needs to be kept un-der surveillance at the networks interconnection

point.Between these two methodologies monitoring

all the loads or only the networks interconnection point sometimes there is the need of a differentapproach. Indeed, for example inside a big manufac-turing plant, it is possible to have circuits of the IPD

explored by different sub-companies with some ofthem affecting the others with poor PQ, leading toequipment degradation and misfunction, and also todifficulties to determine the responsibility and thedistortion and problems sources. To overcome situa-tions like the aforementioned, it is necessary aglobal perspective of these problems including theknowledge of the network structure and of the most

problematic or sensible loads and also a new approach to the standards application. Therefore, inthis paper, we will present a new concept of applica-tion for the IEEE Standard 519-1992 in industrialenvironments achieved through the spreading ofnetworked remote acquisition systems.

Proceedings of the 6th WSEAS International Conference on Power Systems, Lisbon, Portugal, September 22-24, 2006 244

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This paper is organized as follows. Section 2 presents the relevant standards used in electric en-ergy power distribution. Section 3, introduces themain effect of the electrical energy disturbances inindustrial plants. Section 4, describes the new ap-

proach monitoring concept for application of thosemain standards. Section 5, shows experimental re-sults of a cement industry power plant with the ap-

plication of the IEEE Standard, and finally conclu-sion remarks are made.

2. Most Relevant StandardsAlthough distortion problems happen particularly inthe final customer, this problematic issue has otherimplications to be considered: the production,

propagation and resolution of this type of distur-

bances. The harmonics increasing disturbancesbrought a set of standards (resulting from previousguidelines), recommendations and limits, to assurethe compatibility between equipment, devices and

power distribution systems [4].According to the International Standards, the

norms 1000 of the International ElectrotechnicalCommission (IEC) define the current and voltageharmonic levels that must not to be exceeded. TheIEC 61000-3-2 Standard foresees limits for the cur-rent harmonics components emission in equipment(class grouped) for lesser than 16 A rms (per phase).

For equipment with current superior to 16 A, thisStandard recommends the application of the IEC61000-3-4. [4]

Norms IEC-1000-2-2 and IEC-1000-2-4 specifythe voltage harmonic levels to be respected at theinterconnection point of low voltage distributionnetwork, for public and industrial customers, respec-tively. [4]

The European Standard EN 50 160:1994 givesthe main characteristics of the voltage, includingharmonics voltage, in the customer delivery pointfor low and medium voltage under normal operating

conditions. [4]However, the main reference for this subject is

the American Standard that was presented by theIEEE in the recommendation 519-1992: IEEERecommended Practices and Requirements for Har-monic Control in Electric Power Systems, initially

proposed in 1981 and revised in 1992 [5].The earlier version, IEEE 519-1981, established

levels of acceptable voltage distortion for typicaldistribution systems. However, with the increase inindustrial usage of adjustable speed drives, rectifi-ers, and other nonlinear loads, it became apparentthat a rewrite of the IEEE 519 was necessary, with aspecific focus on the relation between harmonic

voltages and harmonic currents flowing within in-dustrial plants. IEEE 519-1992, the result of this re-write effort, sets forth limits for harmonic voltageson the utility transmission and distribution system,as well as for harmonic currents within industrialdistribution systems.

This Standard describes the main causing har-monic distortion phenomena, indicates measuringmethods and limits of distortion. The approach fol-lowed diverse from the IECs, because it sates thatthe established limits values should be measured inthe Point of Common Coupling (PCC), and not ineach individual equipment. Furthermore, it recom-mends two distinct criteria for harmonics limit val-ues: a) the quantity of harmonic currents, which acustomer can set up in the network distribution, has

become limited; b) the voltages harmonic distortion

level present in the power supplied by the energydeliverer to the customer has been limited. [5]These limit values are dependant of several vari-

ables and concepts namely the interconnectionpoint PCC, the short circuit current at PCC (ISC), themaximum demand load current at PCC for a periodof 15 or 30 minutes (IL) and the requested total dis-tortion (TDD - Total Demand Distortion) are

based on the maximum demand load current (fun-damental frequency component), as well as on ameasure of the total harmonic distortion (THD) ofthe current at the PCC for the total connected load

[5]. Obviously, the bigger is the ISC relatively to thecurrent load, the greater will be the permissible cur-rent distortions, because they will distort the voltageat the PCC with less intensity. Whenever the voltagelevel increases the acceptable limits diminish.

For this recommendation, it is of no interest whatoccurs inside the installation, but what it reflects ex-ternally, when the other costumers are hardwiredwith the same feeding network. However, it rela-tively defines the guidelines for current harmoniclevels and voltage distortions to the transmissionlines, distribution and interconnection point with the

customers.

3. Harmonic Effects on the Industrial

Electrical Power SystemThe harmonic distortion effect is evident, in the

peak values increase (that can lead the insulationsystem to rupture),in the rms values increase (leadsto augment the losses) and in the voltage and currentfrequency spectrum increase (vibrations and me-chanical exhausting) [2] the current harmonics

circulation produces the heating of the transformers,


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feeding cables, motors, alternators and power factorcompensation capacitors.

Also, the cathode devices and illumination sys-tems start to flicker due to the presence of harmonicvoltage (consequence of the increase of the harmon-ics current circulation through the network imped-ance), and the unexpected start of protection de-vices, wrong operation in sensitive electronicequipments (computers, command and controlequipments, etc.) and errors in the values of themeasurement equipment (e.g. electronic industrial

balances, hospital equipment, etc.) can occur [3].The most significant disturbances take place withconducted phenomena, but in specific circum-stances, they can also happen with radiated phe-nomena.

The long term effect cannot be directly related

with the explicit form of the waveform distortion presence, because it is a sufficiently dissimulatedeffect, corresponding overall to a speed up of equip-ment exhaustion, that can lead to the reduction of itsusefulness [3].

Since the symptoms origin is unknown, it isthen necessary to look for potentially generatingsources of harmonics in the plant installation.Firstly, the effect will be felt inside the plant beforeappearing in the electrical distribution network.

The harmonic pollution presents ominous effectfor various equipments of the electric installations,

even if its consequences are not immediately ob-servable. Therefore, it is a good policy to keep thelevels of this distortion within the established bandof the main standards and in order to do this it must

be implemented corrective options concerning thispollution reduction.

4. Disturbances Analysis in the Indus-

try SectorToday it is frequently necessary to continuously

monitor the power network systems performance inorder to characterize possible disturbance impactsand put into practice the main standards [7]. Aglobal and complete system data analysis must beflexible, capable of operating with a large variety ofmonitoring equipment and keeping a database thatcan be shared between different applications and bethe most adequate to control the normative limits[6]. This concept is illustrated in Fig. 1. The archi-tecture presented depicts a possible PQ integratedmonitoring and analysis system organization. Thistype of system must be flexible enough so it can be

adapted to different users applications necessities.

PlantInformation

Normative Indices

Waveform

Acquisitions

Data Load

Data base

Monitorizaode eventos

Anlise de tendncia

dos dados

AnliseHarmnica

AnliseEnergtica

Anlise

estatstica

Analysis Program

Modules of:

Report

Report

Report

Report

Report

DATA

PQ indices

Data

Conditioning

StatisticalAnalysis

EnergyAnalysis

HarmonicsAnalysis

Data TrendAnalysis

EventsRegisters

Fig. 1 Data acquisition system architecture for PQmonitoring and analysis for standards application.

In addition, the system must be able to create auto-matic reports based on the legal normative limits.

Any PQ monitoring and control system mustnecessarily include the calculation of algorithms for

the power flows and PQ indices. The methods con-sidered in literature are several and a number of re-searchers have proposed different approaches for the

power calculation in electrical network with har-monic distortion. Each of these theories has their in-dividual usefulness, but has also its individualdrawbacks. Unfortunately, the different approachesdiverge and emphasize distinct qualities that aresuited to particular applications, ranging from thatof calculating the required capacities of compensat-ing equipment to locating distortion sources in net-works. Alternative approaches can be confusing to

those in the industry wishing to use it for specifying,designing and service equipment. There is a demandfor one method that alone could be capable of satis-fying all the practical needs. The approach of theIEEE Working Group on Non-Sinusoidal Situationis the most appropriate to support the implementa-tion control of the IEEE Standard 519-1992, be-cause it is the best approach in terms of practicalutility in the search of an optimal compensating to-

pology for an industrial plant [8].The recent work of this IEEE Working Group,

suggests a set of practical definitions, with a simple

form to determine the distortion power as a function


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of the terms: total, fundamental and harmonic con-stituents [8].

The voltage and current waveforms rms values,VRMS and IRMS, considering the mean value equal tozero, can be separated in two terms, fundamentaland other harmonic frequency components, throughexpressions (1) and (2):

2 2 21RMS hV V V= + with

2

2h h

h

V V

=

= , (1)

and

2 2 21RMS hI I I = + with

2

2h h

h

I I

=

= . (2)

Then:

( ) ( ) ( ) ( )2 2 2 22

1 1 1 1h h h hS V I V I V I V I = + + + , (3)

or regrouping:2 22

1 NS S S= + , (4)where S1 is Fundamental Apparent Power and SN

Non-fundamental Apparent Power, being thesegiven by:

( ) ( )

( )

2 221 1 1 1 1 1 1

2 2 21 1 1 1 1 1

cos

S V I V I

V I sin P Q

= = +

+ = +, (5)

and

( ) ( ) ( )2 2 22

1 1N h h h hS V I V I V I = + +22

NN QP += . (6)

In (6), the term (V1Ih) is called the Current Dis-tortion Power, (VhI1) the Voltage Distortion Power

and (VhIh) the Harmonic Apparent Power being di-vided in: Total Harmonic Active Power,Ph, and To-tal Harmonic Non-active Power, Qh, as exemplified

by (7):

( )22 2 2

h h h h hS V I P Q= = + . (7)

One other expression can be achieved, when (6)is divided by (5):

2 2 2 2

1 1 1 1

N h h HS I V S

S I V S

= + +

, (8)

origin of the Normalized Non-fundamental Distor-

tion Power, when it is rewritten on the form:

( ) ( ) ( )2

2 2 2

1

Ni v v i

STHD THD THD THD

S

= + +

. (9)

The three terms of (9) appropriately represent thecurrent THD, the voltage THD and the product ofthe previous two.

The application of the IEEE Working Groupmethod results in useful information, classified asfundamental apparent power (S1) and fundamentalreactive power (Q1); this one indicates the value ofthe correction capacitors for the fundamental power

factor, to be used in the passive filters configuration.The non-fundamental apparent power (SN) and the

non-fundamental reactive power (QN), provide indi-cations of the required capacity for the dynamiccompensator for the non-fundamental distortion,when used alone.Theterm (V1Ih) indicates the levelof the current distortion, and the term (VhI1) presentsthe same information relatively to the voltage. Onthe other hand, the THDs taxes can be taken fromthese power values [8]. Such values are extremelyimportant for the good application of this IEEEStandard since any monitoring system must have acorrect evaluation of the PQ implemented in indus-trial environment.

To increase the interest concerning the area ofPQ prevention by the application of normative ruleswith the presented methodology, a small dimensionsmodular system is proposed in [3]. This modularsystem, depicted in Fig. 2, is focused on three-phase

power networked systems study. Its main character-istics are: current and voltage precision transducers(3% in a bandwidth of 20 kHz); synchronous ac-quisition of all signals in real time, by user requestor by pooling on every 15 minutes, in 5 periods

packages, with 40 s sampling rate, correspondingto 2500 points on a 100 ms time space, with a ultrafast microcontroller; Ethernet remote access andlarge local data storage capacity based on anIPC@CHIP SC12 (BECK IPC GmbH); low costsystem modules. These systems allow an easy dis-semination in IPD and a short investment recovery

time. The modular architecture system was devel-oped in order to be easily expanded within the in-dustry, depending on its necessities. [3]

Dados

Device / Load

Device / Load

Device / Load

Device / Load

Device / Load

Device / Load

Device / Load

AcquisitionModule

AcquisitionModule

AcquisitionModule

AcquisitionModule

EEtthheerrnneett//IIPP

oorrIInndduussttrriiaall

NNeettwwoorrkk

Data Monitoring,Treatment, Analysis

and Storage.

EEtthheerrnneett//IIPP

oorrIInndduussttrriiaall

NNeettwwoorrkk

AcquisitionModule

Fig. 2 Remote acquisition system implementationin industrial power distributions.


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Taking this into account, many acquisition sys-tems can be used, specially in primary and secon-dary of power transformer(s), in PCC(s) and next tocritical or special machines, susceptible to producedistortion or that need more rigorous feeding condi-tions.

5. IEEE Standard Application in a

Cement Industry Case StudyThe application domain of the analysis and monitor-ing integrated system presented is extremely vast.At this point, it is presented its use in the IPD of acement production centre (CIMPOR Cement Indus-try, S.A.), in order to perform a waveform distur-

bance analysis. This production unit has a hugepower plant and possesses a complex electrical in-

stallation. Although the limits imposed by the powersupplier and by the IEEE Standard were both re-spected at the PCC, there were malfunction prob-lems in critical equipments of the production line 3cooling system (Fig. 3). It was then decided tomonitor this production line. This installation ismade up of three step-down transformers (T1, T2,T3), whose primary is fed by a distribution indus-trial link (6 kV). T1 secondary supplies the MotorControl Center 1 (MCC1). T2 supplies the MCC2and T3 is a double secondary transformer that sup-

plies the MCC3 frequency converter.The MCC1 essentially supplies fans powered by

induction motors controlled by Variable FrequencyDrives (VFD). There are six 75 kW fans, two of132 kW and two of 160 kW. It also supplies low

power induction motors and a local cabinet.The MCC2, supplies twelve VFD of 37 kW each

(that control the induction motors of the cooling sys-tem fans), oil pumps, sleeve filter extractors andcompressors (also powered by induction motors).

The two MCCs also have power factor compen-sation.

The MCC3 frequency converter is made up by atwelve pulses rectifier (two six pulses) and corre-sponding inverter for supplying the induction motor(785 kW) of the drawing fan.

Fig. 3 Production line 3 cooling system schema.

5.1 Analysis ResultsFor study and analysis purposes, the collected re-sults (Fig. 4) regarding the new approach systemmonitoring [3] are confronted by the reference stan-dards IEEE Std. 519-1992 [4, 5].

From a global point of view, disturbance levelspresented in the medium-voltage link (6 kV) are notadjusted for this sort of system distribution. Thereare voltage and current harmonic disturbance valuesabove the maximum suggested for the IEEE Stan-dard. The current harmonic disturbance value ishigh, mainly in the 250 Hz and 350 Hz frequencyamplitudes. However, in the AA interconnection

point the current sum provides a harmonic levelslightly below the IEEE Standard reference for this

power class.Voltage harmonic distortion levels above normal

values are present in point A'' and B'' in Fig. 3. Thisdisturbance caused malfunctioning on more sensi-tive equipment connected to these network points.The most critical current component frequency val-ues presented were for 250 Hz and 350 Hz. The au-dit results suggested then the use of solutions thatminimize the 5th and 7th order harmonic current.Consequently it was proposed a solution based on

passive filters, that taking into account the installa-tion type and its functioning, was the most appro-

priate.The interaction between the voltage distortion

and the current harmonic amplitudes can be ob-served, because T1 secondary with 63.4% load level

presents greater voltage distortion than T2 secon-dary with 15% load level, although T1 and T2 areidentical transformers.

In the specific case of the T3 secondary, it is im- portant to mention that, although the rectifiers ab-sorbed current harmonic levels are above standard

boundaries, working in such conditions is not

Fig. 4 Daily analysis/Load Diagram window forthe IEEE 519-1992 Standard.


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problematic, because the load is made up by onlyone equipment. Furthermore, it is verified that volt-age distortion values for both secondaries of T3transformer are above the suggested standard limits.

The power factor presented in the IPD produc-tion line 3 has a compatible value with the requestedfor the energy distribution company, correspondingto an efficient use of the IPD energy (see Fig. 4).

6. ConclusionThe most effective way to meet harmonic distortionlimits is to filter the harmonics at each individualload. But if it is attempted to monitor and enforcethe PQ limits at each individual load, the most co-mmon available technology is incapable of doingthe work and very high-cost equipment will be

needed.On the other hand, distortions produced by driveslocated inside the customer facility, normally willnot affect the drive's functions, and high distortionat particular points does not necessarily result inout-of-limit distortion at the PCC. The IEEE Std.519-1992 recommends values of harmonic distor-tion for the electric power system (not for individualloads), focusing on the PCC with the consumer-utility interface.

However, between those two approaches, some-times there is the need to monitor and enforce the

PQ in some areas inside plant installations. It was presented the case of a big plant, where there are parts of the IPD explored by different sub-companies and with some of them affecting the oth-ers with poor PQ, causing malfunctions on criticalequipments. In this case, it was decided to imple-ment the guidelines of IEEE Std. 519-1992 not onlyat the PCC but at carefully chosen internal PCCsinside the plant. For this objective, it was developedand used by the authors [3] a low cost monitoringsystem that detected and quantified harmonic pollu-tion problems in the analysed circuits. Based on the

analysis results, corrective measures were sug-gested.

It should also be mentioned that the remote useof the monitoring system, through the internal

power plant computer network, as well as the im- plementation of the system without disturbing la-bouring on the manufacture unit, was very appreci-ated by maintenance people and plant administra-tion.

To conclude, the proposed approach and the usedintegrated system proved large viability in industrialenvironment, in low and medium-voltage, for agood control of the rates of normative limit values.

Acknowledgement:The authors gratefully thank the CIMPOR Indstriade Cimentos, S.A. - C. P. Souselas for providing tothe opportunity of on site data acquisition.

References:[1] KENNEDY, B., MCGRANAGHAN, M., Power

Quality Contracts in a Restructured Competi-tive Electricity Industry, Electrotek Concepts,PQNetwork.

[2] DUGAN,R.,MCGRANAGHAN,M.,WAYNE,H.,

1999, Electrical Power Systems Quality, 265pp., McGraw-Hil, NewYork, USA.[3] TROVO, J. P.,Harmonic Distortion Monitor-

ing and Analysis Integrated Systema System-atic Approach for the Industrial Sector (inPortuguese), M.Sc Thesis, Faculty of Scienceand Technology of the University of Coimbra,Portugal, 2004.

[4] MCGRANAGHAN,M.,Overview of Power Qual-ity Standards, Electrotek Concepts, PQNet-work.

[5] IEEE STD. 519-1992, IEEE Recommended Practices and Requirements for HarmonicControl in Electric Power Systems, IEEE In-dustry Applications Society/Power EngineeringSociety.

[6] MELHORN,C.,MCGRANAGHAN,M,Interpreta-tion and Analysis of Power Quality Measure-ments, IEEE Transactions on Industry Applica-tions, vol. 31, n. 6, pp. 1363-1370, November1995.

[7] SABIN, D., MCGRANAGHAN, M., SUNDARAM,A., A Systems Approach to Power QualityMonitoring for Performance Assessment, Pro-ceedings of the 7th Annual Canadian Electric-ity Forum on Power Quality and Power Har-monics, Toronto, Canada, May 1997.

[8] PRETORIUS,J.,WYK,J.,SWART,P., An Evalua-tion of Some Alternative Methods of PowerResolution in a Large Industrial Plant, IEEETransactions on Power Delivery, vol. 15, n. 3,

pp. 1052-1059, July 2000.


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