“AWARENESS ON HARMONICS PROBLEMS,

CAUSES, CONQUENCES AND PERFECT

SOLUTIONS”

Santosh MalaniDEM (PQ)

UNDERSTANDING POWER QUALITY PROBLEMS:

Equipment demands this BUT gets this…..

Spike

Sag

Surge/SwellPower Fails

Frequency

ChangeTransients Harmonic Distortion Noise

Most commonly

detected problem

POWER QUALITY PROBLEMS: HARMONICS

What are harmonics?Voltage or current waveform that are not at the desired 50 Hz fundamental frequency, but at same multiple frequency

POWER QUALITY PROBLEMS: HARMONICS

By simple definition Harmonics are any “Non-Linear” Current or Voltage in an electrical distribution systemMultiple frequency supply in a single conductor

POWER QUALITY PROBLEMS: HARMONICS

WASTAGE OF POWER

POWER QUALITY PROBLEMS: HARMONICS

CAUSES

Resistive linear loads such as the incandescent light bulb result in sinusoidal waveforms.However Electronics switching loads means devices that rectifies AC Voltage into a DC Voltage causes Non-linear loadsFew Examples are … a) Power supply in a computer/PLC/Automatization Diode-capacitor/SCR input section of power supplies.

b) Variable frequency Drivesc) Welding Machine Cycles

POWER QUALITY PROBLEMS: TRANSIENTSPOWER QUALITY PROBLEMS: HARMONICS

CAUSES

POWER QUALITY PROBLEMS:

HARMONICS CAUSES

Equipments Consequences

Capacitors Blown fuses, reduced capacitor life

Motors Reduced motor life, inability to fully load motor, Mechanical fatigue

Fuses/breakers False/spurious operation, damaged components

Transformers Increased copper losses, reduced capacity

Electrical Cables Reduced Current Capacity, Insulation Failures

Electronic loads Malfunction, Card Failures

every 10°C rise in the operating temperatures of Cables, motors or capacitors can cut equipment life by 50%

POWER QUALITY PROBLEMS:

HARMONICS CAUSES

OVER HEATING ,EDDY CURRENT LOSSES RISES AT FULL LOAD

IMPACT ON TRANSFORMERS

IMPACT ON TRANSFORMERS

IMPACT ON ELECTRONICS

IMPACT ON MOTORS

50 Hz Rotation

5th HarmonicRotation

More Heating, Vibrations and Humm Noise in Motors Reduces Life.

POWER QUALITY PROBLEMS: TRANSIENTSIMPACT ON MOTORS

Motor damage, losses (heating) from “negative sequence currents”.

High harmonics = low total power factor (utility penalties)“Negative Sequence Current”

• Tries to Rotate Motor in Opposite Direction

• Causes Motor Losses, Heating and Vibrations

Rotating Sequence according to Harmonic Number

+ 1st 7th 13th 19th Rotates with Fundamental

0 3rd 9th 15th 21th Does Not Rotate

- 5th 11th 17th 23rd Rotates Against Fundamental

IMPACT ON PROCESS

Malfunction in Machine operation

Unknown failures in Machine

POWER QUALITY PROBLEMS: TRANSIENTSIMPACT ON POWER CABLES

If we refer the standards IEC 60364-5-52, the cable de-

rating is about 60% due to harmonic phenomena.

IMPACT ON POWER CABLES

Above 350 Hz skin effect will become significant causing additional

loss and heating In Cables and all conductors and Joints .

POWER QUALITY PROBLEMS: TRANSIENTSIMPACT ON POWER FACTOR

Effect of Harmonics on measured, true Power Factor

THDi (%) PF

20 0,981

50 0,894

100 0,707

POWER QUALITY PROBLEMS: TRANSIENTSREACTIVE POWER

Reactive Power

Power merely absorbed & returned in load due to its reactive properties

Unit is Volt-Amp-Reactive (VAR)

True (Real) Power

Power actually used by a load

Unit is Watt (W)

Apparent Power

Total power that appears to be consumed by an AC circuit.

Contains both used and absorbed/returned

Unit is Volt-Amp (VA)

HARMONIC CONSEQUENCES

• High measurement errors in metering equipment

• Spurious operation of fuses, circuit-breakers and other protective equipment

• Voltage glitches in computers systems resulting in lost data

• Electromagnetic interference with TV, radio, communication & telephone

• Damage and disruption to standby generators and associated AVR control equipment

HARMONICS CONCLUSION

• Harmonic currents cause problems both on the supply

and within the distribution system.

• The effects and the solutions are very different and need to be addressed separately.

POWER QUALITY PROBLEMS: TRANSIENTSSOLUTIONS ON PQ PROBLEMS

Survive

- De-rate Up-stream equipments

Isolate

- Isolated the harmonic rich load

- Use of Line Reactors or Isolation transformers

Divert

- Use tuned filters to reduce selected harmonics

Cancel

- Use phase shifting techniques to cancel load generated harmonics

Neutralize- Active Harmonic Filter

SOLUTIONS ON PQ PROBLEMS

Passive Harmonic Filters - Passive Harmonic Filters consist of passive components such as resistors, inductors and capacitors and can eliminate only one harmonic frequency for which it is designed.

Active Harmonic Filters – Active Harmonic Filters are electronic devices that eliminate the undesirable harmonics on the network by inserting negative harmonics into the network. The active filters are normally available for low voltage networks. The active filters consist of active components such as IGBT-transistors and eliminate many different harmonic frequencies

POWER QUALITY PROBLEMS: TRANSIENTSSOLUTIONS ON PQ PROBLEMS

Active Harmonic Filter

Passive Filters Tuned Filters

POWER QUALITY PROBLEMS: TRANSIENTSUNIQUE SOLUTIONS

THANK YOU