M2

Power Quality Training Courses

Harmonics and Interharmonics

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Module 2 Harmonics and Interharmonics

1 INTRODUCTION Two sources of voltage and current distortion are dealt with in this seminar: harmonics (mainly) and interharmonics. Their sources and effects, as well as possible methods of their mitigation and measuring are presented.

1.1 General aims The seminar participant should obtain information on the theoretical background of the distorted signals analysis, sources of distortion with special regard to power electronic systems, effects of distorted voltages and currents, methods for location of distortion sources in a power system, distortion reduction methods, measurement principles, standardization, formulating contacts, etc. Most of the lecture subject will be supplemented with laboratory experiments and exemplified by analysis of real cases.

1.2 Target groups This module’s target group are mainly: − end-users of equipment; − designers; − installers or contractor of installations; − electric networks operators; − equipment sellers and services providers in the electricity sector.

2 SPECIFIC AIMS AND TOPICS The pathway of learning consists of a 2 days course, subdivided in sections (with different duration), with these contents and related aims. 1st day Contents

Aims

Contents

Aims

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Voltage & current harmonics Power theories in electrical circuits Passive filters of high harmonics Supplying knowledge concerning basics of distorted signals analysis, sources of distortion, with special regard to power electronic systems, effects of distorted voltages and currents, methods of locating distortion sources in a power system, passive methods for harmonics mitigation 2nd day Active power filter Interharmonics Harmonic measurements Standardization Neutral line and transformer sizing in the environment of distorted current and voltages Case studies (laboratory) Contract Supplying knowledge concerning principles of measuring, standardization, formulating contracts. Use of the obtained knowledge to analysis and solving problems in harmonics, as well as to practical measurements in laboratory.

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Below there’s a detailed overview of the course contents. 2.1 Pathway of learning flow chart

Time progression (hours)

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COURSE DETAILED PROGRAM

First day: 60 mins

Participants registration

5 mins

Opening, informations, course introduction

70 mins

Section 1: Introduction − Basic terms and definitions − Description of the disturbance (sources, power electronic converters, effects) − Methods of voltage and current harmonics mitigation Modality: Lesson and discussion

45 mins

Power theories in electrical circuits Modality: Lesson, computer laboratory and discussion

15 mins

Coffee break

60 mins

Section 2:High harmonics passive filters Modality: Lesson and discussion

Second day: 45 mins

Section 3: Active power filters Modality: Lesson, laboratory and discussion

45 mins

Interharmonics Modality: Lesson and discussion

15 mins

Coffee break

45 mins

Section 4: Measuring techniques and instrumentation (measuring instruments, measuring signal analysers) Modality: Lesson, laboratory and discussion

15 mins

International, European and other standards and regulations Modality: Lesson and discussion

45 mins

Neutral line and transformer sizing in the environment of distorted current and voltages Modality: Lesson and discussion

15 mins

Coffee break

75 mins

Section 5:Voltage and current distortion – case studies Methods of analysis Modality: Lesson, laboratory and discussion

30 mins

Final discussion and conclusions, End of the course, user satisfaction survey (user’s questionnaire), Confirmations of attendance

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GENERAL NOTES − − − −

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each day there will be two coffee breaks according to the seminar program; at the beginning of the course the lecturer will explain course aims and at the end he will verify their fulfilment; the course will be divided in theoretical and practical sections; at the end of the lessons, a user satisfaction survey will help the lecturer in monitoring the course quality.

TEACHING METHODS

Teaching methods are summarized in three main moments: − − −

knowledge transfer (Lesson) topics exposure by the lecturer with the help of slides and presentation of practical cases; deepening/learning verification (Discussion) general discussion stimulated by the lecturer (also during the lesson) to verify knowledge transfer; practical training, laboratory activities; group work

During all the sections, the lecturer will always attend, with teaching and/or activity coordination duty.

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DIDACTIC MATERIAL AND TOOLS

The didactic tools which will be used by the lecturers will be: − Blackboard − Video-projector − Notebook − Microphone The lecture room will be suitable to allow the use of all the above listed didactic tools and to enable group work for the attendants. Each user will receive, during the registration, a folder containing: − course program; − lecture notes containing all or part of the lecture slides; − LPQIVES knowledge database access personal key. All this didactic material, and eventually some additional electronic tools, will be available also in electronic format at: http://lpqi.org/custom/1036/. The folder will also include a user satisfaction questionnaire and a knowledge test (which will be both filled and submitted at the end of the course).

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EXISTING KNOWLEDGE REQUIREMENTS

The following (on the basic level) shall be prerequisite for the participant: − −

electric circuits theory: AC circuits electric machines

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electric power engineering; power system power electronics electric metrology. ACQUIRED COURSE KNOWLEDGE

The knowledge acquired during the course should be sufficient for: − − − − − −

identification of the distortion nature distortion source identification disturbance assessment by means of measuring evaluation of technical and economic effects of disturbance proposing remedial measures formulation of contract between the supplier and consumer of electric power on the basis of the existing standards and regulations

8 OTHER Both in Germany and in Poland this seminar is the part of the system of obtaining professional degrees in power quality. Complete information is available: 9

ANNEXES - MIDAS REPORT

Press 1. PR-00007, Heydt, G, Power Quality Engineering, JEEE, Sep 2001 Encompassing most areas of electric power engineering, from generation to utilization, power quality engineering has been a topic of interest from the inception or the power engineering field. Here, the author describes how some contemporary factors have made it the subject of more focused interest

2. PR-00008, Peng, FZ, Harmonic sources and filtering approaches, JEEE 22 basic filter configurations for compensating current-source and voltage-source nonlinear loads

3. PR-00013, Pierce, L, Transformer Design and Application Considerations for Nonsinusoidal Load Currents, IEEE Transactions on Industry Applications, 01/06/1996 Transformer design and application considerations for nonsinusoidal load currents

4. PR-00014, Yin, W, Failure mechanism of winding insulations in inverter-fed motors, IEEE Electrical Insulation Magazine, Nov/Dec 1998 The failure of magnet wires under repetitive pulses as seen in inverter-fed motors cannot be attributed to a single factor but is a result of the combined effects of partial discharge, dielectric heating, and space charge formation. Voltage overshoots produced by PWM drives may be above discharge inception voltage. Partial discharge may therefore be present in inverter-fed motors. In addition to partial discharge, pulses with a fast rise time and high frequency enable the insulation to generate local dielectric heating, which increases the local temperature. The degradation rate of the insulation is therefore increased. Furthermore, the fast rise and fall of pulses make it possible for space charges to accumulate in the winding insulation and on its surface

5. PR-00015, Key, T, Lai, J, Costs and benefits of harmonic current reduction for switchmode power supplies in a commercial office building, IEEE Transactions on Industry Applications Harmonic currents generated by modern office equipment cause power system heating and add to user power bills. By looking at the harmonic-related losses in a specific electrical system-representing a commercial building-energy costs are quantified. The analysis shows that building wiring losses related to powering nonlinear electronic load equipment may be more than double the losses for linear load equipment. Current-related power losses such as I2R, proximity of conductors and transformer winding eddy currents (I2h2 ) are considered. The cost of these losses is compared to the cost of reducing harmonics in the equipment design. Results show that an active-type harmonic elimination circuit, built into the common electronic equipment switch-mode power supply, is cost-effective based on energy loss considerations alone

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6. PR-00016, Caramia, P, Carpinelli, G, Di Vito, E, Losi, A, Verde, P, Probabilistic evaluation of the economical damage due to harmonic losses in industrial energy system, IEEE Transactions on power delivery, Vol 11 No 2 Apr The problem of harmonic loss evaluation is of growing interest among power system engineers, both for the increase of operating costs and the decrease of the useful life of the system components. The paper addresses this problem with a probabilistic approach to take into account the randomness of current and voltage harmonics; a method for evaluating the expected value of the operating costs and of the premature aging costs is presented. A numerical application to a test system is also discussed, showing the viability of the proposed approach and the significance of the results; in particular, the aging costs turn out to be unaffected by the type of probability density function describing the harmonics

7. PR-00018, Caramia, P, Carpinelli, G, La Vitola, A, Verde, P, On the economic selection of medium voltage cable sizes in nonsinusoidal conditions, IEEE Transactions on power delivery, Jan 2002 Selection of cable size in the nonsinusoidal conditions is only based on ampacity considerations without any attention to the cost of the losses that will be suffered in the cable life. Since the cost of these losses (fundamental plus harmonics) can assume significant values, the selection of a cross section higher than required for ampacity considerations can result in a large reduction of cost. This paper proposes a method which allows the optimal economic selection of medium-voltage cables in nonsinusoidal operating conditions; it takes into account the initial investment costs and the Joule losses costs, including the additional costs due to current harmonics. It employs simplified expressions similar to those adopted by the IEC Standard in sinusoidal conditions, being the harmonic presence taken into account by a proper definition of a harmonic loss factor and by the introduction of harmonic coefficients to be predicted. Numerical applications to medium-voltage cables are developed and discussed in order to show the sensitivity of the cable optimum size to variations in the coefficients that characterize the harmonic presence

8. PR-00020, Gurney, J, Hughes, B, Li, C, Neilson, B, Xu, W, Virtual PQ troubleshooter, IEEE power & energy magazine, may/june 2003 The authors describe a prototype instrument that locates the sources of power quality disturbances and is geared toward power system troubleshooting and management.

9. PR-00025, n /a, Conditionnement facile pour un problème complexe, JEEE, April 2004 Artcle inspired from section 3.3.3. of the Power Quality Application Guide on active harmonic conditioners.

Publication 10. REP-00002, 2004, 1-9 Power Quality Glossary, Application note The glossary of main technical terms used in PQ

11. REP-00005, 2003, 3-2-1 Harmonic measurement Measuring in harmony with harmonics Harmonic measurement, methododlogy, metersm principle, errors, analysis.

12. REP-00007, 2003, 3-3-2 Harmonic Mitigation Transformers Application note about transformer losses and ways of their mitigation

13. REP-00008, 2003, 3-3-4 Active Rectifiers Active rectifiers topology, operation, application

14. REP-00010, 2004, 3-5-2 Transformer selection and rating, Application Note Sizing transformers to harmonics, K factor, factor K.

15. REP-00011, 2004, 3-5-3 Harmonics and asynchronous motors Harmonics effects on motors. Losses. Motor derating

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16. REP-00028, 2003, 6-2-2 Power quality measurement technology: fit for the future, Application Note Somehow Fluke philosophy of PQ measurement - hints. Subjects: - The main problems - A comparison of the approaches: former vs. future - New opportunities - New tools for the power quality measurement technology of the future

17. REP-00036, 2001, 3-1 Harmonics. Causes and Effects, Application Note Application guide about harmonics basics. Causes, effects, mitigation.

18. REP-00037, 2004, 3-1-1 Interharmonics, Application Note Interharmonics; sources, effects, measurement, standards, mitigation

19. REP-00039, 2002, 3-2-2 True RMS - The only true measurement, Application note True RMS concept. Measurement errors.

20. REP-00040, 2003, 3-3-1 Passive Filters, Application note Basics of passive filters. Reactive compensation. Measurement first.

21. REP-00041, 2002, 3-3-3 Active Harmonic Conditioners, Application note Principle of active filter. Topologies. Applications basics

22. REP-00042, 2003, 3-5-1 Neutral Sizing in Harmonic Rich Installations, Application note Sizing neutrals in the presence of harmonics - what standards say (IEC60364 -5-52)

23. REP-00055, 2003, Practical Method to Determine Additional Load Losses due to Harmonic Currents in Transformers with Wire and Foil Windings, Application note A method is presented to determine the additional load losses in transformers caused by harmonic currents. Several blackbox short circuit tests at different harmonic frequencies have to be conducted on existing transformers or have to be simulated in the design stage.

24. REP-00058, 2003, SWITCH MODE POWER SUPPLY, Application note Application note about switch mode power supplies. Design concept. Topology of converters. Performance - control modes. Standards. Effects.

25. REP-00059, 2003, Practical approach to non linear parameter estimation of six pulse converter with voltage source inverters, Application note Description of parameters of six-pulse bridge converters in three-phase systems, influence of the topology of the system, experimental set-up for determining parameters. The goal of this study is to simplify modeling and predict behaviour and influence of converters.

26. REP-00069, 2003, Analysis of neutral conductor current in a three phase supplied network with non linear single phase loads, Application note This paper describes the effect of harmonics and unbalanced power supply and load on the current in the neutral conductor. Results from measurements are discussed.

27. REP-00071, 2003, On line monitoring of the neutral conductor current in a three phase supplied network with non linear load for different power supply and load conditions, Application note This paper describes the effect of harmonics and unbalanced power supply and load on the current in the neutral conductor. Measurement results are discussed. Using a programmable power source, arbitrary voltage waveforms are generated, independently for each phase. Each phase is loaded by non-linear loads. Phase currents and the current in the neutral conductor are analyzed for different configurations.

28. REP-00074, 2003, Analysis of electrical and power quality parameters of IT equipment, Application note Measurements of electrical and PQ parameters of non-linear single-phase loads are discussed. These loads consist of information-technology (IT) equipment. The non-linearity results from the bridge rectifier. The influence of the state of the equipment is studied. Currents in the phase conductors and the neutral conductor are analyzed.

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29. REP-00078, 2003, Harmonic disturbances in networks, and their treatment - ect 152, Application note Problems of harmonics, including their causes and the most commonly used solutions.

30. REP-00080, 2003, The singularities of the third harmonic - ect 202, Application note Discussion of the phenomenon: origin, overload of the neutral conductor, third harmonic in transformers. Possible remedies.

31. REP-00084, 2003, Active harmonic conditioners and unity power factor rectifiers - ect 183, Application note Various standard, classical and new solutions to tackle harmonics, unity PF rectifiers, active harmonic conditioners, hybrid active harmonic conditioners, "shunt type" active harmonic conditioners.

32. REP-00087, 2003, Harmonics upstream of rectifiers in UPS - ect 160, Application note Harmonics in supply networks, thyristor Graetz-bridge rectifier, minimization of harmonic disturbances, future systems: non-polluting UPS equipment and de-polluting converters.

33. REP-00099, 2003, LV circuit-breakers confronted with harmonic, transient and cyclic currents - ect 182, Application note Discussion on the replacement of thermal-magnetic circuit breakers by electronic devices. Review of LV circuit breakers, harmonic currents, transient and cyclic currents and electronic circuit-breakers.

34. REP-00101, 2003, Power supply of lighting circuits - ect 205, Application note Analysis of the different lamp technologies and the main technological developments in progress. Features of lighting circuits and their impact on control and protection devices, they discuss the options concerning which equipment to use.

35. REP-00105, 2003, Harmonic distortion in electric supply system - Application note no. 3, Application note Harmonic distortion - subjects: 1. The ideal supply 2. The growth in harmonic distortion is inevitable 3. How harmonic distortion can affect your equipment 4. Capacitor resonance can magnify harmonic problems 5. Power factor correction in the presence of harmonics 6. The measures of harmonic distortion 7. Harmonic standards 8. Harmonic analysis 9. Reduction of harmonics

36. REP-00117, 2000, Harmonics, Transformers and K-Factors, Brochure Transformers used to supply IT equipment and other non-linear loads need to be de-rated to between 60 and 80% of their nominal capacity. This technical note explains why, and how to determine the correct factor.

37. REP-00118, 2000, Harmonics in practice, Brochure Over recent years, harmonics have become a serious problem in many industrial and commercial installations. Solving these problems requires careful analysis of the causes and a good understanding of the sources and behaviour of harmonics in the installation. Once understood, there is a range of counter measures available to improve the system performance. The aim of this technical note is to illustrate how practice matches theory by reference to examples of real measurements.

38. REP-00125, 2002, Specification guidelines to improve power quality immunity and reduce plant operating costs, Paper There are many useful IEEE and IEC standards that support the design of chemical and petrochemical plants. This article brings relevant Power Quality standards information together and provides recommendations in areas not yet covered in current standards. Circuit configurations for cost saving solutions are provided.

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39. REP-00127, 2002, Power quality indices and objectives. Ongoing activities in CIGRE WG 36-07, Paper This paper gives an overview of the ongoing activities in CIGRE WG36-07: "Power quality indices and objectives". It introduces the considerations supporting the need for power quality indices and objectives in the present context of deregulation of the electricity industry. Experts generally agree on the need for standardized quality indices allowing to monitor and to report power quality in a common format. However, concerning quality objectives the need is more likely for different levels of quality that can match customers expectations and the price they are wilting to pay for electricity. Some practical limitations to voltage quality monitoring are also discussed. The status of the work within the working group is described for harmonics, flicker, unbalance and voltage dips.

40. REP-00131, 2002, Managing harmonics - a guide to EA engineering recommendation G5/4, Application note This Guide is a simple authoritative introduction to good practice in the application of variable speed drives, soft starters and load regulators in compliance with the requirements of the United Kingdom electricity supply utilities. It is the result of work undertaken by GAMBICA members, interpreting the appropriate documents. The Guide considers the installation of single or multiple drive systems, and provides information on the manner in which applications for connection should be made with the appropriate utility. The guide should be read in conjunction with the Electricity Association (EA) Engineering Recommendation G5/4, which was introduced on the 1st. The Recommendation will be followed by an extensive supporting guide ETR 122. The intention of the new EA Engineering Recommendation G5/4 is to try to ensure that the levels of harmonics in the Public Electricity Supply do not constitute a problem for other users of that supply.

41. REP-00132, 2002, Variable speed drives and motors - motor shaft voltages and bearing currents under PWM inverter operation, Application note This Technical Report has been produced to meet a demand for an authoritative guide on good practice in the application of motors on Pulse Width Modulated (PWM) inverter supplies with respect to shaft voltages. It is the result of a study carried out by GAMBICA and REMA taking note of well-established fundamental theory, technical papers, and carrying out specific investigations. The information given, while it can be applied to motors and inverters in general, is specific to current generation products of member companies. This report principally considers the effects of shaft voltages developed by the voltage source PWM inverter. It supplements IEC 60034-17: 1998 [1], which provides additional information on other important aspects including: voltage rating, torque derating, additional losses, noise and maximum safe operating speed. This report covers motors and inverters installed with a separate cabling system connecting the components together; it is not wholly applicable to inverters integrated into a motor design, generally now available up to 7,5 kW.

42. REP-00133, 2001, Variable speed drives and motors - motor insulation and PWM inverter drives, Application note The higher stresses are dependent on the motor cable length and are caused by the fast rising voltage pulses of the drive and transmission line effects in the cable. The guide was produced by a working group of GAMBICA (Variable Speed Drives Group) and REMA, which are the associations for variable speed drive and electric motor manufacturers respectively.

43. REP-00143, 2002, Switch mode power supply, Paper The principle of SMPS and its harmonic performance

44. REP-00144, 1996, Guide to quality of electrical supply for industrial installations. PART 1: Types of disturbances and relevant standards, Brochure (Document available in the library of Katholieke Universiteit Leuven) 1. Scope 2. Introduction to the concept of electromagnetic compatibility (EMC) 2.1. Definition of EMC 2.2. Basic concepts 2.3. Compatibility, emission and immunity levels 2.4. The concept of electromagnetic environment 3. Types of disturbances, origins and effects www.lpqi.org

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3.1. General classification 3.2. Harmonics 3.3. Interharmonics 3.4. Voltage fluctuations 3.5. Voltage dips and short (supply) interruptions 3.6. Voltage unbalance - asymmetry 3.7. Power frequency variations 3.8. Transient overvoltages 3.9. Mains siganlling 3.10. Reference to HF conducted and LF and HF radiated disturbances 4. Coordination strategies among the involved parties 4.1. Evaluation of the disturbance emission level 4.2. Immunity of equipment 4.3. Mitigation techniques 4.4. Prediction studies for installation requirements 4.5. An approach to measurement criteria 5. Main standards and othter EMC publications 5.1. Recent developments in the approach to evaluating EMC coordination 5.2. Relevant EMC standards on EMC 5.3. CENELEC and national EMC standards and publications 5.4. Relevant publication from other international bodies dealing with EMC 6. Glossary of terms and definitions 7. Abbreviations 8. References Appendix A. Disturbance compatibility levels in figures A-1. Electromagnetic compatibility levels for low-, medium- and high-voltage public distribution networks A-2. Electromagnetic compatibility levels for indoor industrial plants

45. REP-00153, 2003, Analysis of electrical and power quality parameters of IT-equipment The electrical behaviour of PC’s is studied. All tested devices show bad power quality parameters and do not comply with IEC61000-3-2. Monitor settings have a rather high influence on the current while I/O actions are hardly noticeable. An increasing number of the same PC’s gives a noticeable improvement of the power quality parameters and a nearly proportional increase of the current. Also a nearly proportional increase of the neutral conductor current is found.

46. REP-00154, 2002, Total harmonic current of a large number of non-linear single phase loads The cumulative harmonic currents of a large number of non-linear single phase loads, particularly PC’s and monitors, are investigated experimentally. An analytical model and simulations show there is a significant attenuation of the current harmonics above the third when a large number of such loads is considered. This is verified in this paper by means of measurements.

47. REP-00155, 2003, Analysis of the neutral conductor current in a three phase supplied network with non-linear single phase loads, Application note This paper describes what factors (i.e. load and supply) have an important effect on the neutral conductor current. It is shown that an asymmetry up to 10° or an unbalance of 10% in the power supply has only a minor effect on the rms-value of the neutral conductor current. An unbalance in load conditions increases the neutral current. Harmonics in the power supply voltage highly affect the rms-value of the neutral conductor current.

48. REP-00156, 2003, Analysis of electrical and power quality parameters of ITequipment, Application note This paper describes measurements of electrical and power quality parameters of non-linear single phase loads, specifically information technology (IT) equipment where the non-linearity is caused by the bridge rectifier of the switching power supply. The paper includes the study of the influence of the working mode of a particular equipment (such as: monitor settings, I/O actions,...) and the analysis of the phase and neutral conductor currents of a three phase supplied network loaded with IT-equipment.

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