TRANSFORMER ENCYCLOPAEDIA HARMONICS PRESENTED BY PROF VG PATEL

TRANSFORMER ENCYCLOPAEDIA HARMONICS PRESENTED BY PROF. VG PATEL

TRANSFORMER ENCYCLOPAEDIA HARMONICS Harmonics Friday, February 19, 2021 PROF. V. G. PATEL 2

TRANSFORMER ENCYCLOPAEDIA HARMONICS Friday, February 19, 2021 PROF. V. G. PATEL 3

TRANSFORMER ENCYCLOPAEDIA HARMONICS Presentation Flow: — What are Harmonics? — How are Harmonics generated? — Why are harmonics harmful? — The Measurements of harmonics — Harmonics in supply systems Friday, February 19, 2021 PROF. V. G. PATEL 4

TRANSFORMER ENCYCLOPAEDIA HARMONICS What are harmonics? v Ideal supply system has pure sinusoidal voltages and currents at the fundamental frequency v Harmonics are generated in the system due to non linear loads v Non linear loads do not draw current proportional to the voltage v Non sinusoidal supply voltage and current are result of sum of all harmonics present. v These harmonics are sinusoidal signals of integral multiples of the fundamental frequency. v These have different amplitude and phase relation w. r. t. fundamental. Friday, February 19, 2021 PROF. V. G. PATEL 5

TRANSFORMER ENCYCLOPAEDIA HARMONICS NORMAL SINUSOIDAL WAVEFORM Friday, February 19, 2021 PROF. V. G. PATEL 6

TRANSFORMER ENCYCLOPAEDIA HARMONICS Friday, February 19, 2021 PROF. V. G. PATEL 7

TRANSFORMER ENCYCLOPAEDIA HARMONICS Friday, February 19, 2021 PROF. V. G. PATEL 8

TRANSFORMER ENCYCLOPAEDIA HARMONICS Friday, February 19, 2021 PROF. V. G. PATEL 9

TRANSFORMER ENCYCLOPAEDIA HARMONICS Friday, February 19, 2021 PROF. V. G. PATEL 10

TRANSFORMER ENCYCLOPAEDIA HARMONICS Friday, February 19, 2021 PROF. V. G. PATEL 11

TRANSFORMER ENCYCLOPAEDIA HARMONICS Friday, February 19, 2021 PROF. V. G. PATEL 12

TRANSFORMER ENCYCLOPAEDIA HARMONICS How are harmonics generated? There are plenty of non linear loads in industrial and domestic environments — Static power converters , which take current in impulses. — Arc furnaces, Arc welding sets and ovens — mercury vapor lamps, high pressure sodium vapor lamps and metal Halide lighting etc. — Switching or phase controlled AC to DC power supplies, battery chargers and UPS for computers — Controlled drives and computer controlled machines. — Transformers operating near saturation. — Non linearity of BH curve. — Induction furnaces and electrolysis plants. — Electronic Dimmers, fan and speed regulators. Friday, February 19, 2021 PROF. V. G. PATEL 13

TRANSFORMER ENCYCLOPAEDIA HARMONICS Friday, February 19, 2021 PROF. V. G. PATEL 14

TRANSFORMER ENCYCLOPAEDIA HARMONICS ELECTRIC ARC FURNACE Friday, February 19, 2021 PROF. V. G. PATEL 15

TRANSFORMER ENCYCLOPAEDIA HARMONICS Friday, February 19, 2021 PROF. V. G. PATEL 16

TRANSFORMER ENCYCLOPAEDIA HARMONICS Friday, February 19, 2021 PROF. V. G. PATEL 17

TRANSFORMER ENCYCLOPAEDIA HARMONICS Friday, February 19, 2021 PROF. V. G. PATEL 18

TRANSFORMER ENCYCLOPAEDIA HARMONICS Friday, February 19, 2021 PROF. V. G. PATEL 19

TRANSFORMER ENCYCLOPAEDIA HARMONICS Friday, February 19, 2021 PROF. V. G. PATEL 20

TRANSFORMER ENCYCLOPAEDIA HARMONICS Friday, February 19, 2021 PROF. V. G. PATEL 21

TRANSFORMER ENCYCLOPAEDIA HARMONICS Friday, February 19, 2021 PROF. V. G. PATEL 22

TRANSFORMER ENCYCLOPAEDIA HARMONICS Friday, February 19, 2021 PROF. V. G. PATEL 23

TRANSFORMER ENCYCLOPAEDIA HARMONICS Friday, February 19, 2021 PROF. V. G. PATEL 24

TRANSFORMER ENCYCLOPAEDIA HARMONICS Friday, February 19, 2021 PROF. V. G. PATEL 25

TRANSFORMER ENCYCLOPAEDIA HARMONICS i) HARMONIC DETECTION METHODS Load current detection i. AF= i. Lh It is suitable for shunt active filters which are installed near one or more non-linear loads. ii) Supply current detection i. AF= KS i. Sh Is the most basic harmonic detection method for series active filters acting as a voltage source v. AF. iii) Voltage detection It is suitable for shunt active filters which are used as Unified Power Quality Conditioners. This type of Active Filter is installed in primary power distribution systems. The Unified Power Quality Conditioner consists of a series and a shunt active filter. Friday, February 19, 2021 PROF. V. G. PATEL 26

TRANSFORMER ENCYCLOPAEDIA HARMONICS WHY HARMONIC ANALYSIS ? When a voltage and/or current waveform is distorted, it causes abnormal operating conditions in a power system such as: v Voltage Harmonics can cause additional heating in induction and synchronous motors and generators. v Voltage Harmonics with high peak values can weaken insulation in cables, windings, and capacitors. v Voltage Harmonics can cause malfunction of different electronic components and circuits that utilize the voltage waveform for synchronization or timing. v Current Harmonics in motor windings can create Electromagnetic Interference (EMI). Friday, February 19, 2021 PROF. V. G. PATEL 27

TRANSFORMER ENCYCLOPAEDIA HARMONICS v. Current Harmonics flowing through cables can cause higher heating over and above the heating that is created from the fundamental component. v. Current Harmonics flowing through a transformer can cause higher heating over and above the heating that is created by the fundamental component. v. Current Harmonics flowing through circuit breakers and switch-gear can increase their heating losses. v. RESONANT CURRENTS which are created by current harmonics and the different filtering topologies of the power system can cause capacitor failures and/or fuse failures in the capacitor or other electrical equipment. v. False tripping of circuit breakers ad protective relays. Friday, February 19, 2021 PROF. V. G. PATEL 28

TRANSFORMER ENCYCLOPAEDIA HARMONICS Friday, February 19, 2021 PROF. V. G. PATEL 29

TRANSFORMER ENCYCLOPAEDIA HARMONICS Friday, February 19, 2021 PROF. V. G. PATEL 30

TRANSFORMER ENCYCLOPAEDIA HARMONICS Different Techniques for Harmonic Measurement Introduction: Problem arises when a customer generates significant harmonic waveform distortion that affects adjacent utility customers. Because all customers can be regarded as harmonic producers to some extent, utilities may find it difficult to pinpoint the right location of the harmonic source, particularly when resonant networks come into play. Utilities may need to carry out measurements at a number of locations involving suspected customers before they can decide the source of the problem to start discussing remedial measures. Friday, February 19, 2021 PROF. V. G. PATEL 31

TRANSFORMER ENCYCLOPAEDIA HARMONICS Different Techniques for Harmonic Measurement From the electric utility perspective, the general objectives for conducting harmonic measurements may be summarized as follows: • To verify the order and magnitude of harmonic currents at the substation and at remote locations where customer harmonic sources may be affecting neighboring installations • To determine the resultant waveform distortion expressed in the form of spectral analysis • To compare the preceding parameters with recommended limits or planning levels Friday, February 19, 2021 PROF. V. G. PATEL 32

TRANSFORMER ENCYCLOPAEDIA HARMONICS Different Techniques for Harmonic Measurement • To assess the possibility of network resonance that may increase harmonic distortion levels, particularly at or near capacitor banks • To gather the necessary information to provide guidance to customers in controlling harmonic levels within acceptable limits • To verify efficacy of implemented harmonic filters or other corrective schemes • To determine tendencies in the voltage and current distortion levels in daily, weekly, monthly, etc. , basis Techniques for Harmonic Measurement. Friday, February 19, 2021 PROF. V. G. PATEL 33

TRANSFORMER ENCYCLOPAEDIA HARMONICS Friday, February 19, 2021 PROF. V. G. PATEL 34

TRANSFORMER ENCYCLOPAEDIA HARMONICS Harmonics in supply systems • Electricity generation is always sinusoidal • Harmonics are generated at the loads • Drops in line and transformer impedances cause distortion in voltages • Voltages therefore have lower harmonics (typically up to 5 - 10%) • Currents may have large harmonic content depending on nature of load (typically 30 - 40%) Friday, February 19, 2021 PROF. V. G. PATEL 35

TRANSFORMER ENCYCLOPAEDIA HARMONICS Friday, February 19, 2021 PROF. V. G. PATEL 36

TRANSFORMER ENCYCLOPAEDIA HARMONICS Effects of Harmonics on Operation of Various Equipments Modern industrial and commercial networks are increasingly influenced by significant amounts of harmonic currents produced by a variety of nonlinear loads like variable speed drives, electric and induction furnaces, and fluorescent lighting, uninterruptible power supplies and massive numbers of home entertaining devices including personal computers. Friday, February 19, 2021 PROF. V. G. PATEL 37

TRANSFORMER ENCYCLOPAEDIA HARMONICS Effects of Harmonics • Over heating of Transformer Winding • Over heating of Transformer Load • Increases Iron Losses • Increases Transformer Insulation Stresses • Increases Skin effect • Increases Hysteresis and Eddy current Loss • Creates Direct current in Primary winding • Resonance possibility at 31 harmonic frequency on transformer winding. • Power correction capacitors can cause series and parallel resonance effects on system • If harmonic is generates which excites a system resonance, amplification of that harmonic may occur. Friday, February 19, 2021 PROF. V. G. PATEL 38

TRANSFORMER ENCYCLOPAEDIA HARMONICS Friday, February 19, 2021 PROF. V. G. PATEL 39

TRANSFORMER ENCYCLOPAEDIA HARMONICS 1) Transformer: (A)Thermal Effects: All of these currents are sourced through service transformers. A particular aspect of transformers is that, under saturation conditions, they become a source of harmonics. Delta–wye or delta–delta-connected transformers trap zero sequence currents that would otherwise overheat neutral conductors. The circulating currents in the delta increase the rms value of the current and produce additional heat. This is an important aspect to watch. Currents measured on the high-voltage side of a delta-connected transformer will not reflect the zero sequence currents but their effect in producing heat losses is there. Friday, February 19, 2021 PROF. V. G. PATEL 40

TRANSFORMER ENCYCLOPAEDIA HARMONICS In general, harmonics losses occur from increased heat dissipation in the windings and skin effect; both are a function of the square of the rms current, as well as from eddy currents and core losses. This extra heat can have a significant impact in reducing the operating life of the transformer insulation. Transformers are a particular case of power equipment that has experienced an evolution that allows them to operate in electrical environments with considerable harmonic distortion. In industry applications in which transformers are primarily loaded with nonlinear loads, continuous operation at or above rated power can impose a high operating temperature, which can have a significant impact on their lifetime. Friday, February 19, 2021 PROF. V. G. PATEL 41

TRANSFORMER ENCYCLOPAEDIA HARMONICS (B) Neutral Conductor Overloading: In single-phase circuits, return currents carrying significant amounts of harmonic components flow through transformer neutral connections increasing the RMS current. Furthermore, zero sequence currents (odd integer multiples of 3) add in phase in the neutral. Therefore, the operation of transformers in harmonic environments demands that neutral currents be evaluated in grounded-wye connected transformers to avoid the possibility of missing the grounding connection as a consequence of Overloading. In balanced three-phase, four-wire systems, there is no current on the neutral, for which the presence of neutral currents under these conditions should be attributed to the circulation of zero sequence harmonics, which are mostly produced by single-phase power supplies. Friday, February 19, 2021 PROF. V. G. PATEL 42

TRANSFORMER ENCYCLOPAEDIA HARMONICS In systems that are not entirely balanced, the unbalanced current circulates on the return (neutral) conductor. Because this conductor is usually sized the same as the phase conductors for being able to handle unbalanced currents comfortably, it may experience overheating if those currents are subsequently amplified by zero sequence currents. Large numbers of computers in office buildings make a formidable source of harmonic currents produced by their electronic switched power supplies. A common practice is to size neutral conductors to carry as much as two times the RMS current that phase conductors can take. Monitoring temperature increase on the neutral conductor of transformers might be a good start to detect whether zero sequence harmonic currents are not overstressing neutral connections. This is true as long as the system does not incur increased levels of current unbalance that would produce a temperature rise in neutral conductor temperature. The overall effect can lead to decreased transformer lifetime. Friday, February 19, 2021 PROF. V. G. PATEL 43

TRANSFORMER ENCYCLOPAEDIA HARMONICS (1) Capacitor Banks: (A) Overstressing: (B) Resonant Conditions: (2) Electronic Relays: (3) Lighting Devices: (4) Telephone Interference: (5) Rotating Machines: (6) Solid State Devices: (7) Generator: (8) Distribution systems Conductors: (9) Energy Metering Equipment: Friday, February 19, 2021 PROF. V. G. PATEL 44

TRANSFORMER ENCYCLOPAEDIA HARMONICS Effects of Harmonics on power cables If we refer the standards IEC 603645 -52, the cable derating is about 60% due to harmonic phenomena. Friday, February 19, 2021 PROF. V. G. PATEL 45

TRANSFORMER ENCYCLOPAEDIA HARMONICS Friday, February 19, 2021 PROF. V. G. PATEL 46

TRANSFORMER ENCYCLOPAEDIA HARMONICS Effects of Harmonics on power cables Above 350 Hz skin effect will become significant causing additional loss and heating In Cables and all conductors and Joints. Friday, February 19, 2021 PROF. V. G. PATEL 47

TRANSFORMER ENCYCLOPAEDIA HARMONICS Harmonics can be a big source of “low Power Factor” Friday, February 19, 2021 PROF. V. G. PATEL 48

TRANSFORMER ENCYCLOPAEDIA HARMONICS Friday, February 19, 2021 PROF. V. G. PATEL 49

TRANSFORMER ENCYCLOPAEDIA HARMONICS Friday, February 19, 2021 PROF. V. G. PATEL 50

TRANSFORMER ENCYCLOPAEDIA HARMONICS Friday, February 19, 2021 PROF. V. G. PATEL 51

TRANSFORMER ENCYCLOPAEDIA HARMONICS Friday, February 19, 2021 PROF. V. G. PATEL 52

TRANSFORMER ENCYCLOPAEDIA HARMONICS Friday, February 19, 2021 PROF. V. G. PATEL 53

TRANSFORMER ENCYCLOPAEDIA HARMONICS Friday, February 19, 2021 PROF. V. G. PATEL 54

TRANSFORMER ENCYCLOPAEDIA HARMONICS Friday, February 19, 2021 PROF. V. G. PATEL 55

TRANSFORMER ENCYCLOPAEDIA HARMONICS Friday, February 19, 2021 PROF. V. G. PATEL 56

TRANSFORMER ENCYCLOPAEDIA HARMONICS Friday, February 19, 2021 PROF. V. G. PATEL 57

TRANSFORMER ENCYCLOPAEDIA HARMONICS HARMONIC STANDARDS International Electro-technical Commission (IEC) European Standards. - EN 61000 -3 -2 Harmonic Emissions standards were first published as IEC 55 -2 1982 and applied only to household appliances. It was revised and reissued in 1987 and 1995 with the applicability expanded to include all equipment with input current 16 A per phase. However, until January 1 st, 2001 a transition period is in effect for all equipment not covered by the standard prior to 1987. - The objective of EN 61000 -3 -2 (harmonics) is to test the equipment under the conditions that will produce the maximum harmonic amplitudes under normal operating conditions for each harmonic component. To establish limits for similar types of harmonics current distortion, equipment under test must be categorized in one of the following four classes. Friday, February 19, 2021 PROF. V. G. PATEL 58

TRANSFORMER ENCYCLOPAEDIA HARMONICS CLASS-A: Balanced three-phase equipment and all other equipment except that stated in one of the remaining three classes. CLASS-B: Portable electrical tools, which are hand held during normal operation and used for a short time only (few minutes) CLASS-C: Lighting equipment including dimming devices. CLASS-D: Equipment having an input current with special wave shape ( e. g. equipment with off-line capacitor-rectifier AC input circuitry and switch Mode power Supplies) and an active input power 600 W Friday, February 19, 2021 PROF. V. G. PATEL 59

TRANSFORMER ENCYCLOPAEDIA HARMONICS IEEE 519 -1992 United States Standards on harmonic limits - IEEE limits service entrance harmonics. - The IEEE standard 519 -1992 limits the level of harmonics at the customer service entrance or Point of Common Coupling (PCC). - With this approach the costumer’s current distortion is limited based on relative size of the load and the power supplier’s voltage distortion based on the voltage level. IEEE 519 and IEC 1000 -3 -2 apply different philosophies, which effectively limit harmonics at different locations. IEEE 519 limits harmonics primarily at the service entrance while IEC 1000 -3 -2 is applied at the terminals of end-user equipment. Therefore, IEC limits will tend to reduce harmonicrelated losses in an industrial plant wiring, while IEEE harmonic limits are designed to prevent interactions between neighbors and the power system. Friday, February 19, 2021 60 PROF. V. G. PATEL

TRANSFORMER ENCYCLOPAEDIA HARMONICS IEEE-519 provision for penalty for high harmonics beyond limits - TANGEDCO implemented Friday, February 19, 2021 PROF. V. G. PATEL 61

TRANSFORMER ENCYCLOPAEDIA HARMONICS K Factor = Factor useful for transformers design and specifically from transformers that feed Adjustable Speed Drives. ONCE THE SHORT CIRCUIT RATIO IS KNOWN, THE IEEE CURRENT HARMONIC LIMITS CAN BE FOUND AS SPECIFIED IN TABLE I OF THE IEEE 519 -1992 POWER QUALITY STANDARDS. USING THE ABOVE EQUATIONS VALUES OF IDIVINDUAL AND TOTAL VOLTAGE AND CURRENT HARMONIC DISTORTION CAN BE COMPUTED AND COMPARED WITH THE IEEE LIMITS. Friday, February 19, 2021 PROF. V. G. PATEL 62

TRANSFORMER ENCYCLOPAEDIA HARMONICS Effect of Harmonics on measured, true Power Factor THDi (%) PF 20 0, 981 50 0, 894 100 0, 707 Friday, February 19, 2021 PROF. V. G. PATEL 63

TRANSFORMER ENCYCLOPAEDIA HARMONICS CONCLUSIONS v. Solid State Power Control results in harmonic pollution above the tolerable limits. v. Harmonic Pollution increases industrial plant downtimes and power losses. v. Harmonic measurements should be made in industrial power systems in order (a) aid in the design of capacitor or filter banks, (b) verify the design and installation of capacitor or filter banks, (c) verify compliance with utility harmonic distortion requirements, and (d) investigate suspected harmonic problems. v. Computer software programs such as PSPICE and SIMULINK can be used in order to obtain the harmonic behavior of an industrial power plant. v. The series LC passive filter with resonance frequency at 4. 7 is the most popular filter. Friday, February 19, 2021 PROF. V. G. PATEL 64

TRANSFORMER ENCYCLOPAEDIA HARMONICS CONCLUSIONS Contd…. . v The disadvantages of the tuned LC filter is its dynamic response because it cannot predict the load requirements. v. The most popular Active Filter is the parallel or shunt type. v Active Filter technology is slowly used in industrial plants with passive filters as a hybrid filter. These filters can be used locally at the inputs of different nonlinear loads. v Active Filter Technology is well developed and many manufactures are fabricating Active filters with large capacities. v A large number of Active Filters configurations are available to compensate harmonic current, reactive power, neutral current, unbalance current, and harmonics. v The active filters can predict the load requirements and consequently they exhibit very good dynamic response. v LC tuned filters can be used at PCC and the same time active filters can be used locally at the input of nonlinear loads. Friday, February 19, 2021 PROF. V. G. PATEL 65

TRANSFORMER ENCYCLOPAEDIA OPEN FORUM Friday, February 19, 2021 66

TRANSFORMER ENCYCLOPAEDIA THANQ Friday, February 19, 2021 67