The document discusses harmonics, their sources, effects and mitigation techniques. Some key points: 1) Harmonics are generated by non-linear loads and can cause overheating, equipment failures and power quality issues. Common sources are power electronic equipment, arc furnaces and electronic ballasts. 2) Harmonics can have instantaneous effects like resonance, noise and interference or longer term impacts like increased losses and equipment degradation. Proper mitigation is needed to control costs. 3) Passive and active filters are commonly used to mitigate harmonics. Passive filters include tuned and detuned filters while active filters can dynamically cancel harmonics. Case studies show filters reducing currents and distortion while improving power factor.

1. Harmonics Impact and
Mitigation
R.Panneer Selvam, B.E.,M.I.E,
Former Superintending Engineer
Tamil Nadu Electricity Board
Mob- +91 9444389547
Mail id : panneer.rps@gmail.com

11. LIFT

12. CHILLER PANEL

13. LIGHTING PANEL – I1

14. SERVICE LIFT 2

15. Harmonic Generation
Harmonics are mainly produced by
non-linear loads which draw
current of a different wave form
from the supply voltage
(see fig. )
The spectrum of the harmonics
depends on the nature of the load.
Harmonic voltages occur across
network impedances resulting
distorted voltages which can
disturb the operation of other
users connected to the same supply
Degradation of network voltage caused by a non-linear load.

16. Main sources of harmonics
Industrial loads
Power electronic equipment:
drives, rectifiers (diode or
thyristor), inverters or switching
power supplies;
Loads using electric arcs:
arc furnaces, welding machines,
lighting (discharge lamps,
fluorescent tubes).
Starting motors using electronic
starters and
power transformers energisation
also generates (temporary)
harmonics.
Domestic loads with
power inverters or
switching power supplies
such as television,
microwave ovens, induction
hotplates, computers,
printers,photocopiers,
dimer switches,
electrodomestic
equipments, fluorescent
lamps.

17. Harmonic levels
The sources usually generate
odd harmonic components
(see fig. in next slide ).
Power transformer
energisation, polarised
loads (half-wave rectifiers)
and arc furnaces generate
even harmonics in addition
to odd harmonics
components.

Inter harmonics are sinusoid
components with frequencies
which are not integer ultiples of
the fundamental component
(they are located between
harmonics).
They are due to periodic or
random variations in the power
drawn by various devices such as
arc furnaces, welding machines
and frequency inverters (drives,
cycloconverters).

18. Characteristics of certain harmonics generators

19. Characteristics of certain harmonics generators

20. Harmonic Impact on Electrical Network
Higher usage of of “Energy Efficient” power Electronics
loads ( Nonlinear loads) pollute Electrical networks with
harmonics
In extreme cases excessive harmonic may lead to
failure of equipment
The usage of PF correction Capacitors further
complicates the situation
Capacitors don’t generate harmonics but may result in
“Resonance”, when interact the presence of harmonics
with the existing network.

21. EFFECT OF HARMONICSIN ELCTRICAL NETWORK
 Harmonics have varied effect on the equipment
and devices. The classified as
 Instantaneous Effect , and
 Long Term Effect

22. INSTANTANEOUS EFFECT
Series / Parallel Resonance may happen
Vibration and noise in Transformers, Reactors and Induction
Motors
Mal functioning sensitive electronics devices (PLC Circuits,
Measuring and Lab Equipments )
Increase of zero sequence component – Hot neutral
Interference in communication and control circuit ( Telephone,
control and Monitoring circuit ) Total energy requirement to
perform desired function increases.

23. MEDIUM TERM EFFECTS
Failure of rotating machines
Harmonic rotating field cause pulsating mechanical torque
resulting in vibration and increased mechanical failure.
Reduction in capacitor Life
Draws high current and results in reduction in life.
Premature failure in equipments such as
Transformers , cables etc.
Harmonics causes additional iron loses and and copper
losses ( due to Skin effect)
 Leads to increase in operating Temp
 Cause premature failure

26. COST RELATED TO HARMONIC POLLUTION IN ELECTRICAL
NETWORK
Direct Cost
Indirect Cost

27. DIRECT COST
Increased energy consumption due to higher losses

28. INDIRECT COST
Maintenance Cost
Because of the problems listed above, maintenance activity increases
Due to heating , the insulation of motors degrades, warranting rewinding
and results in increased maintenance cost
Down-time cost
Failure of equipment increases the down time and results in production cost
Losses will be more on continuous process industry like petrochemical
paper and cement industries.
Equipment Replacement cost
High level of harmonics may result in failure of equipment in electrical
network ( Eg. PF correction capacitors, sensitive PLC cards, electronic
devises etc.
Result in replacement cost

29. INDIRECT COST ( Contd.)
Equipment de-rating Cost
When harmonics are present in the network equipments
connected should have immunity level to harmonics
Or, the equipment shall be de-rated.
According to IEC 61000-2-4 electrical networks are classified
as
 Class – 1 - upto 5% THD
 Class – 2 - upto 8% THD
 Class – 3 - upto 10% THD
Equipments to be designed to class 3 network will be costlier
than for class 1 network

30. INDIRECT COST ( Contd.)
Safety cost
Safety criteria is extremely important in modern buildings whether
commercial or residential
Triplen harmonics are odd multiples of third harmonics
Common in Single phase SMPS driven loads like computer, television
and other office equipments
They are abundant in IT parks and modern buildings
The magnitude of neutral current may exceed the line current.
Conventionally designed neutral current may get over-loaded, causing
fire hazard.
This can cause neutral open, and result in dangerous over voltage
across single phase equipments
 Resulting in equipment failure
 Pose a serious risk to life of operating personnal

31. Safety cost
Safety criteria is extremely important in modern buildings whether
commercial or residential
Triplen harmonics are odd multiples of third harmonics
Common in Single phase SMPS driven loads like computer, television
and other office equipments
They are abundant in IT parks and modern buildings
The magnitude of neutral current may exceed the line current.
Conventionally designed neutral current may get over-loaded, causing
fire hazard.
This can cause neutral open, and result in dangerous over voltage
across single phase equipments
Resulting in equipment failure
Pose a serious risk to life of operating personnal

38. HARMONIC MITIGATION SOLUTION
There are several methods of harmonic mitigation
Harmonic mitigation shall provide following
benefits
 Reduce harmonic level to a desired level
 Provide required Capacitive KVAR to improve PF
 Prevent series or parallel resonance

39. TYPES OF HARMONIC FILTERS
Harmonic
Filters
Active
Harmonic
Filters
Passive
Harmonic
Filters
Detuned
Filters
Hybrid
Harmonic
Filters
Tuned
Filters
7 %
14%
Single
Phase
3 Ph
4 wire
3 Ph
3 wire

40. PASSIVE HARMONIC FILTER
 A series combination of reactor (L) and capacitor ( C )
 Impedance based filter
 Filtering capability depends on relative impedance w.r.t network
impedance
 The Reactor blocks the harmonic current flow to the capacitor
 They are further classified as detuned or tuned based on proximity of its
self tuned frequency
 Self resonance frequency related to tuning factor
 Tuning Factor p % =( XL / XC ) * 100
 Tuning Frequency fr (HZ) = fs / (p/100) , where fs is
fundamental frequency.

41. DETUNED FILTER
If the tuning frequency of the filter is lower than 90%of the lowest harmonic
frequency with considerable amplitude, it is called the “Detuned filter”
 Eg. 7% tuning factor corresponds to the resonant frequency of 189 Hz ( fs =
50HZ)
 Is a detuned filter for 5th harmonics ( 250 HZ )
 It acts as capacitor for frequencies lower than its tuning frequency
 As an inductor for higher frequencies
 Series / parallel resonance at frequencies higher than tuned
frequency is eliminated as the filter behaves like an inductor.
 As it behaves like a capacitor for frequencies below tuning
frequencies, care shall be taken to ensure that no significant
harmonic component present below tuning frequency


42. TUNED FILTER
If the resonant frequency of the filter is within 10% of the harmonics
to be filtered
Called as tuned filter
Carry more current as they offer low impedance path
More expensive
Used only in Special cases- where detailed system study was
carried out
Efficiency changes when network is modified.
Several tuned filters are to be used in parallel, if more than one
harmonic frequency to be filtered.

43. APPLICATION CONSTRAINTS FOR IMPEDANCE BASED
(PASSIVE) FILTERS
Sensitive to changes in the network
Cannot handle wide spectrum of harmonic distortion
Sensitive to System frequency changes
Location limitations especially in vicinity of AC / DC drives
Likely to permanently fail in case of sustained harmonic
over load.
Prier Knowledge of harmonic spectrum is required

44. ACTIVE HARMONIC FILTER
• New generation of
harmonic filters
• Very high Speed IGBT
ensuring response time of a
few milliseconds
• Capable of generating wide
spectrum of harmonic
currents to inject into the
network to cancel the
harmonic current drawn
from the source by
nonlinear loads
• Additionally they can
generate both capacitive
and inductive reactive
power in a step-less
manner improving the PF of
the load.

45. HYBRID FILTERS
A combination of detuned
and Active filter
Active filters are used to
handle the dynamically
varying harmonic
component and
Detuned filters handle more
predictable narrow band in
addition to providing
capacitive reactive power
compensation at
fundamental frequency

48. Impact of Harmonics
The consequences of harmonics are linked
 to the increase in peak values (dielectric breakdown),rms values (excessive
overheating) and
 to the frequency spectrum (vibration and mechanical stress) of voltages and
currents.
The effects always have an economic impact resulting from the additional
costs linked to:
 degradation in the energy efficiency of the installation (energy loss),
 oversizing of equipment,
 loss of productivity (accelerated ageing of equipment, unwanted tripping).
 Malfunctions are probable with a harmonic distortion factor of greater than 8 %
of the voltage.
 Between 5 and 8 %, malfunctions are possible.
 Thermal control devices. Indeed, when protective devices of this
type calculate the rms value of the current from the peak value,
there is a risk of error and unwanted operation even during
normal operation with no overload.

49. Impact of Harmonics
Disturbances induced by low current systems (remote control,
telecommunications, hi-fi systems, computer screens, television
sets).
Abnormal vibrations and acoustic noise (LV switchboards,
motors, transformers).
 Destruction of capacitors by thermal overload If the actual
frequency of the upstream capacitor-network system is similar to
a harmonic order, this causes resonance and amplification of the
corresponding harmonic.
Loss of accuracy of measurement instruments
A class 2 induction energy meter will produce in current and voltage,
a 0.3 % additional error in the presence of 5 % of harmonic 5.

50. Impact of Harmonics
Long term effects
Current overload produces excessive overheating and leads to
premature ageing of equipment:
 Overheating of sources: transformers, alternators (through increased
joule and iron losses).
Mechanical stress (pulse torque in asynchronous machines).
Overheating of equipment: phase and neutral conductors through
increased joule and dielectric losses.
Capacitors are especially sensitive to harmonics as their impedance
decreases in proportion to the harmonic order.
 Destruction of equipment (capacitors, circuit breakers,etc.)

51. Impact of Triplen Harmonics
Overload and excessive overheating of the neutral conductor may result
from the presence of third harmonic (and multiples of 3) currents in the
phase conductors which add in the neutral.
The TNC neutral earthing system uses the same conductor for neutral and
protection purposes.
This conductor interconnects the installation earth, including the metal
structures of the building.
Third harmonic (and multiples of 3) currents will flow through these
circuits and produce variations in potential with the following results:
 corrosion of metal parts,
 overcurrent in the telecommunication links between the exposed-conductive-
part of two devices (for example, printer and computer),
electromagnetic radiation causing screen disturbance (computers, laboratory
apparatus).

52. Effects of harmonics and the normal permitted levels

53. Remedial measures

54. Remedial measures

55. Remedial measures

56. Harmonic mitigation in M/S Hindustan Unilever Ltd.

57. Harmonic Filter Erected at HLL

59. CASE STUDY – 5
Jindal Steel & Power Ltd.
DRI-II, Raigarh (MP)
4 Nos.150 Amp AF3 at KILN – 8
Existing Set - up at DRI - II Plant
The major loads in DRI :

DC Thyristor Drives

UPS’s

AC Drives

60. The existing power Distribution in DRI
- No. of KILNs - 4 Nos.
- No. of Power Supply Transformer – 4 Nos.
- Transformer rating – 1.7MVA
- Load Distribution- One Trafo for per KILN.
- Spare Transformer – 1 No.
- Transformer efficiency (@ PF-1, assumed) – 98%

61. Problems Faced by user
- Cable Over heating
- Transformer over heating
- Frequent failure of electronic PCB’s
for unknown reasons
- Frequent tripping of breakers
resulting into interruption in process

62. Performance Results of AF3
Sr.
No
.
Test
Condition
Phase R Y B
1
With One AF3
Connected
Load Current (Amp) 558 A 612 A 560 A
Current T.H.D. % 27.60% 29.40% 28.50%
Power Factor 0.63
2
With Two AF3
Connected
Load Current (Amp) 540 A 590 A 540 A
Current T.H.D. % 7% 10% 10%
Power Factor 0.72
3
With Three
AF3
Connected
Load Current (Amp) 480 A 487 A 482 A
Current T.H.D. % 8% 7.90% 6.90%
Power Factor 0.8
4
With Four AF3
Connected
Load Current (Amp) 340 A 350A 344 A
Current T.H.D. % 7.80% 8% 6%
Power Factor 0.92

63. Customer Delivered Value
Direct
1) Savings in KVA
2) Savings in Transformer losses (KW)
Indirect
3) With AF3 two distribution transformers freed for future expansion
4) Cable temperature reduced
5) Stopped frequent & spurious tripping of MCCBs
6) Spurious blowing of fuses in distribution controlled
7) Due to improvement in power quality, the electronic control systems and
logics are well protected
8) KVA demand is made free for additional usage

64. Summary of AF3 Test Results
• Input currents reduced from 680 A to 350 A per phase.
• Input PF is improved from 0.57 to 0.92
• Input current distortion reduced from 57% to 7-8%
• Input KVA reduced from 489 to 252 KVA
• KVA Released - 237KVA (direct reduction)
• Existing transformer of 1.7 MVA
was supporting 0.97 MW load earlier
Now, it can support 1.56 MW load,
if Harmonics & PF are controlled.

65. • Input currents reduced from 680 A to 350 A per phase.
• Input PF is improved from 0.57 to 0.92
• Input current distortion reduced from 57% to 7-8%
• Input KVA reduced from 489 to 252 KVA
• KVA Released - 237KVA (direct reduction)
• Existing transformer of 1.7 MVA
was supporting 0.97 MW load earlier
Now, it can support 1.56 MW load,
if Harmonics & PF are controlled.

66. Case Study-6
Software Development Company
Sutherland Global Service,
Chennai

67. Problems Experienced
- Frequent failure of Electronic Boards in Servers
and Work Station areas
- Slow down of Network for reason unknown
- Tripping of Generator
- Distribution Transformer getting overheated
Site Condition
Installed Power = 640 KVA
Generator Capacity = 300 KVA

68. Load Current and THDv (measured in UPS panel)
Phases Load Current
without AF3
Load Current
with AF3
R 237 A 182 A
Y 208 A 168 A
B 187 A 150 A
Phases VTHD
without AF3
VTHD
with AF3
R 7.8% 2.6%
Y 8.3% 2.5%
B 7.6% 2.5%

69. THDi (measured in UPS panel)
Phases iTHD
without AF3
iTHD
with AF3
R 62% 12.7%
Y 62.8% 14.5%
B 64.8% 16.5%

70. Results
●
Substantial KVA demand reductions up to 32.16 KVA
●
Issues related with the noise, EMI and RFI in the facility was
eliminated
●
Failure of Electronic Boards in the Server stopped completely
●
Generator and EB Transformer heating issues resolved
●
Generator capacity requirement reduced to half

71. Critical Problems Solved
●
Inoxpa India Limited, Pune – D G Hunting Problem and
Maintenance Cost reduction ( AHF + TVSS + Detuned
reactors + Earthing System Improvement )
●
Savings in the Diesel Consumption, Load running on
Single DG Set and DG Hunting stopped.
●
80 % Electronic Component Failure reduction – reported
by the Customer.

72. Critical Problems Solved
●
Suprabha Industries Limited Lucknou.
●
Load – Seam Welding, Co2 and Spot Welding
●
Product – Fuel Tank, Silencers
●
Problems – Power Factor, High KVAh consumption reported and Heavy
Bills from EB.
●
Solution – AHF + TVSS + Detuned Reactors + transformer
●
Problem Solved and Adopting all solutions in the new plant during
Project Level Itself.
●
Tank Leakage/Rejection % reduced from 30 % to 10 % in the process due
to improvement in the welding Quality.

73. Critical Problems Solved
Vijayshree Industries Limited, Tata Nagar – Transformer
Overheating and Power Factor Issue was there for 5 Years, PF
Improved From 0.55 to 0.85 and Above. Issue Solved. (13 Km
Feeder was separately allotted to the consumer by EB and Detuned
Reactors Installed.)
Electronic PCB Manufacturing Company, Pune –
EB Meter Malfunctioning and Excess billing problem resolved,
(EB - Meter Replacement )
Meter Mfg Company Modified the meter designs Suitable to work
in the high harmonic environment in the year 2001.

74. Critical Problems Solved
Upcoming Challenge 3 – FRP Composites Company, Product
Quality Issue, Product Rejection Problem.
Upcoming Challenge 1– Heavy Fabrication Industry – CNC
Welding Machine Drive failure Problem
Upcoming Challenge 2– CNC Machine Shop, More Component
Rejection Problem
Upcoming Challenge 4 – Pharma Company, Product Qty Weight
Accuracy Issue, Product Rejection Problem.

75. Some of the Symptoms of Poor Power Quality
1 High Demand Charges
2 Power Factor Penalties
3 Unable to Maintain Good Power Factor
4 Computers Crashing
5 Computers Locking Up
6 Computers Memory Losses
7 Dropped Telephone Calls
8 Erratic Equipment Operation
9 Equipment Running Hot
10 Nuisance Tripping

76. Some of the Symptoms of Poor Power Quality
11 Lights Flickering
12 Motor Failures
13 Nuisance Tripping
14 Speed/Setting Drifting
15 Component Failures
16 Equipment Running Hot
17 Power Supply Failures
18 Surge Suppressor/UPS Failures
19 Circuit Board Failures
20 Overheating Transformers

77. Some of the Symptoms of Poor Power Quality
21 Overheating Wires/Conduit / Cables
22 Excessive Neutral Current
23 Disturbed/Wavy Audio-Visual Displays
24 Over-Heating Conductors/Switchboards
25 Persistent Fuse Blowing
26 Short Life of Lamps
27 Mains-Based Timing (clocks run fast)
28 Buzzing/Crackling Audio Systems
29 General Equipment Malfunction
30 Motor Start Problems

78. Some of the Symptoms of Poor Power Quality
31 Erratic control of process performance
32 Weight Accuracy Problem in the Process
33 Dimensional Accuracy Problem
34 More % of Rejection due to Power Issues
35 Hum Noise in the Breakers / Substation
36 Transformer Over Heating / Hum Noise
37 Corona Effect in the HT Lines
38 Life of Equipments is Low
39 Maintenance Cost is High
40 Fault Finding Cost and time is High

79. Some of the Symptoms of Poor Power Quality
40 Fault Finding Cost and time is High
41 Problems due to Unknown Reasons
42 Product production cost High due to
Unknown Reason
43 Poor Product Quality due to Unknown
Reason
44 Frequent Earth Faults
45 Contactor Coil Failure rate is High
46 Any Other Problem ( Unknown Reason )

80. 80
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