Analysis of harmonic at different level on distribution system ,its effect and reduction by using appropriate filters

ANUJ ARORA IIT ROORKEE

MENTOR-MR. ARUN AGARWAL

4:Current and voltage distortion factor and their limit

Content

3: Harmonic Hazards

1: Harmonic Definition

2: Generation of harmonics

5:Methods for Harmonic Mitigation

Study, analysis and reduction of harmonics in unit-3 to unit-8

6:

WHAT ARE HARMONICS – Harmonics are integral multiples of some fundamental frequency that, when

added together, result in a distorted waveform.• superimposed on fundamental• produced by non-linear loads• named by order number "n

Harmonic Definition Harmonic Definition

Example: In a 50 Hz electrical system, 150 Hz is the 3rd harmonic, 250 Hz is the 5th harmonic, and so on.

harmonics

distorted wavefundamental

In fact, any function may be constructed from a sine wave and some number of its harmonics:

Where do they come from?

The power company typically supplies a reasonablysmooth sinusoidal waveform:

Where do they come from?

...but nonlinear devices will draw distorted waveforms,which are comprised of harmonics of the source:

Common sources of Harmonics

Lighting ballasts

UPS systems

MAC and DC drives

IN SHREE CEMENT plant DRIVES are main source of harmonic.

In recent years, as rectifier, variable frequency speed control devices, electric arc, electrized railway and all kinds of power electric devices are being widely used in power grid, the power quality is becoming more and more poor than before because of non-linear, impact and unbalance caused by these loads.Now the harmonic pollution is the main reason of poor power quality.

The Generation of HarmonicThe Generation of Harmonic

Ferromagnetic Satuation Type:

Transformer, Reactor, Mutual inductor etc.

Solid State Switch Type:

Rectifier, inverter etc. The harmonic is mainly related to rectifier pulse. 6-pulse generates 6K±1 harmonic, 12-pulse generates 12K±1 harmonic.

Electric Arc Type:

Electric arc furnace, metal melting device, welding machine etc, harmonic change very fast.

Harmonic HazardsHarmonic Hazards

Power Equipment

Products Money expense

Safety

Harmonic affects safety operation of production lines, and then cause product quality problems, such as Paper production, textile, semiconductor etc.

Capacitor Aging, Reactor burning, motor damage, transformer overheating, communication device damage and power cable aging etc.

Harmonic increases line loss and transformer design capacity, and then cause extra electricity bill and equipment cost.

Harmonic results in misoperation and failure operation of protection relays, and then the control cabinet can’t work normally; there are potential safety hazards of harmonic resonance and fire

The direct effects caused by harmonics

●  Reactive power compensator (TSC) can’t switch on or capacitor burnt.

● Harmonics will cause parallel resonance and series resonance in power grid, it will magnify harmonic, which result in bad power accidents.

The direct effects causedby harmonics

●  Harmonic causes damage of control modules of numerical control machine, PLC and home appliance and office appliance.

The direct effects caused by harmonics

●  Harmonic causes transformer overheat, big noise and even burning; power cable overheat and aging.

The direct effects caused by harmonics

●  Harmonics will cause interference to adjacent communication systems, it will make communication devices generate noise,

reduce communication quality, and even result in data lost.

Harmonic-"Subtle Poison" in power network

● Air pollution, water pollution etc, it can’t result in dead immediately, but its threaten always exists, so, the harmonic pollution to power grid is like environment pollution to human, it is subtle poison.

Harmonic Distortion factors

• Harmonic Distortion is a mathematical way of describing how

non-sinusoidal a wave shape appears.• THD v for voltage harmonics and THD i for current harmonic

measurement.

THD V

Individual distoration limit

5

3

2.5

1.5

1.5

1

IEEE-519 voltage distortion limits

69 Kv and under 69000-161Kv 161 Kv and above

Current and voltage distortion limit

IEEE-519 current distortion limits

Concerning current harmonic distortion,IEEE-519 defines the limits as a function of the ratio between the short-circuit current at the PCC ( Isc) and the average current corresponding to the maximum demand during a period of 12months (IL).

Even harmonics are limited to 25% of the odd harmonic limits. Current distortions that result in a DC offset (e.g., half-wave converters) are not allowed.IEEE-519 practically establishes a joint involvement of the customer and the electric company to maintain harmonic distortion levels within limits that will enable the power distribution systems to operate within safe voltage distortion limits.The most widespread standards for harmonic control worldwide are due to IEEE in the U.S. and IEC (International Electrotechnical Commission) in the European Union.

Methods for Harmonic Mitigation

● large power electrical nonlinear equipments often requires mitigation equipment in order to attenuate the harmonic currents and associated voltage distortion to within necessary limits.

● There are two types of filters:

Passive filtersActive filters

● An LC circuit, tuned to each harmonic order to be filtered, is installed in parallel with the non-linear load . This bypass circuit absorbs the harmonics, thus avoiding their flow in the distribution network.● The passive filter is tuned to a harmonic order close to the order to be eliminated

● Passive filter easily effected by load impedance and can be damage if its overload and its require floor area that is 3 time large than Active filters so people prefer active filter over passive filter.

Passive filters

Active Power filter(APF)

● Active Power Filter Capabilities- Eliminating Voltage and Current Harmonics

Reactive Power Compensation ( power factor improvement) Regulating Terminal VoltageCompensating the Voltage flickering

● Active filter uses harmonic reduction techniques to improve the quality of power, by injecting equal current or voltage distortion into the network but in opposite magnitude, which automatically cancels the actual distortion presented in the circuit and it utilize fast-switching insulated gate bipolar transistors (IGBTs) bridge

Active Power filter

Study, analysis and reduction of harmonics in unit-3 to unit-8

● We measured THD of values only on the cooler bas bar (415 Volt) of all unit because mainly all the VFD or drives are

present at the cooler pcc.●All THD are in %(percentage) , current in ampere and losses in

Watt.● In many of A.C. drive and all d.c. drive because of their low

frequency ALM-35(harmonic measurement meter) can’t measure THD V and THD i . it only work in range of 40 to 50 HZ.(It represent by - in table)

Study, analysis and reduction of harmonics in unit-7

Study, analysis and reduction of harmonics in unit-7

THDv

(%)

THDi

(%)

Cur-rent

(A)

WireCU losses

(W)

THDv

(%)

THDi

(%)

Current

(A)

CU Wirelosses(W)

MotorLosses

(W)

Motor+wireCULooses (W)

FN-8A 5.76 38.1 225 312.8 12 28.2 245 585.2 2481.3 3379.5

FN-9A 5.56 36.3 270 328 14.43 6.16 273 1062 2110.6 3500.6

FN-10 5.53 40.8 180 300.3 13.8 15.9 160 777.2 1305.6 2383.1

FN-11 5.46 58.5 65 39 - - 105 306.6 992.25 1337.8

FN-12 5.26 39.7 190 334.5 12.16 4.86 270 2027 3013.6 5375.5

BOOSTERFAN

7.33 39.03 200 360 7.9 1.86 250 1875 2583.7 4818.7

Kiln M.D. 6.2 62.4 580 2523 - - 500 1125 25000 28648

GRATE-1 4.8 60 50 72 - - 55 183.9 248.05 503.95

GRATE-2 4.9 70 45 46 - - 50 139.1 187.5 372.65

Before DRIVE After DRIVE

Study, analysis and reduction of harmonics in unit-7

THDv (%) THDi (%) Current(A) CU losses(W)

Lighting D.B. 5 6.533 60 81.9

Welding D.B. 5.4 13.733 15 1

Cooler APFC 7.733 44.766 580 1009.2

Cooler transformer with APFC OFF

4.333 13.66 1500 5015.25

Cooler transformer withAPFC ON

7.133 28.1 1420 4494.56

NOTE-1. We found out that after use of APFC electricity bill is decreased but harmonic contents is increase its means APFC is actually enhancing harmonics by decrease impedance for harmonics voltage. 2. If we use filters as place of APFC than along with power factor improvement it’s also decrease harmonic contents.

cooler

apfc-

2

cooler

tran

former

with ap

fc off

cooler

tran

sform

er with

apfc

on

FN-8A

FN-9A

FN-10

FN-11

FN-12 (c

ooler es

p)

kiln M

.D

kiln tr

anform

er with

apfc

off

kiln tr

anform

er with

apfc

on

lighting D

.B

welding D

.B

Booster f

an

0

10

20

30

40

50

60

70

THD v R THD v Y

THD v BTHD v AVG

Series5THD I R

THD I YTHD I B

THD I AVG

LC-20

• Total CU losses=60921.8 W• Total Cu losses per day=60921.8*24=1462.123

KWH per day• 1KWH=3.5 RS• Money loss due to Cu losses =5117 RS per day• If we use filter at the cooler bus pcc than we can

save 15% losses due to harmonics• Saves money per day if we use

filters=5117*0.15=767.61 Rs per day• Saves money per month if we use filters=23030

RS

• Cost of filter to be- 15, 00,000 RS for rating of 400A

• Payback time=15, 00,000/23,030=57 month= 5 year 5 month

• Actually after use of harmonic filter power factor also increase upto 0.98 so if we use harmonic filter then there will be no need of APFC .so we can implement this APFC to another place.

• APFC cost=5, 70,000 RS• PAYBACK TIME=(15,00,000 - 5,70,000)/23,030 =3 YEAR 4 month

1. There will be no false tripping of circuit breaker, relay and fuses due to harmonics.

2. Due to harmonics current wire is overloaded and their temperature increase upto 10 degree C above their normal temperature due to this insulation life decrease upto 50% in motor actually after use of active we increase insulation life of motor and decrease the current in wires so losses also decrease.

3. Power factor improve upto 0.98.

Remark- For remove harmonics and decrease losses in wire, motor and transformer harmonics Filter of 400 A suggested at the cooler bus bar.

And along with this there are other benefits of use the active filters –

UNIT-3 to UNIT-8 Cooler bus (415 V)

Cooler pccBus bar

UNIT-3 UNIT-4 UNIT-5 UNIT-6 UNIT-7 UNIT-8

THD v (%) 10.833 3.4 5.966 6.7 7.133 6.4

THD i (%) 48.866 7.533 16.1 21.166 28.1 18.466

● UNIT-3 and UNIT-7 have THDv and THDi very high.● So firstly we will have to implement Active filter at Cooler pcc bus bar of unit-3 and unit-7.