Deicing of transmisson line by dielectrc losses
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Transcript of Deicing of transmisson line by dielectrc losses
SYNERGY INSTITUTE OF ENGINEERING AND TECHNOLOGY
SEMINAR ON:DE-ICING OF TRANSMISSION LINE BY dielectric losses
Under the guidance of:-Mr. AUROBINDO BEHERA(Asst.prof.)
Presented By:-Bhabani Sankar CharanEE-12-921201230197Electrical engineering
DEPARTMENT OF ELECTRICAL ENGINEERING
CONTENTS1. Introduction2. Need of deicing3. What is dielectric loss? 4. Application of high frequency5. Types of De-icing process6. Principle of ice dielectric heating7. Additional consideration8. Advantages9. Disadvantages10. Conclusion11. References
INTRODUCTION
When accretion of ice takes place over the conductor then icing occurs.
Icing of power transmission lines during winter storms is a persistent problem, causing outages and costing millions of rupees in repair expenses.
Deicing is a process in which ice can removed from the iced wire.
For de-icing of high voltage transmission lines a high frequency excitation at approximately 100kHz proposed.
NEED OF DEICINGEquipment failure
Tilting and collapsing of tower
Economic loss
DIELECTRICA material that conducts electricity poorly or
not.However ,under certain condition ,dielectric
material can breakdown and conduct current.When electric field applied, flow of electron
occurs for that time only.As soon as electric effect is reamed, dipole
condition settles down and again becomes insulator.
What is DIELECTRIC LOSS??A portion of the energy of an alternating
electric field in a dielectric medium that Leads to heat evolution.
Dielectric losses depends on frequency and the dielectric material.
APPLICATION OF HIGH FREQUENCY
Fig 1-De-icing of power lines by applying high frequency high voltage
TYPES OF DE-ICING PROCESS
Deicing using roller
Dielectric heating
Skin effect heating
DE-ICING USING ROLLER
Fig 2-De-icing process using roller
DIELECTRIC HEATING
Fig 3-Equivalent circuit for ice-coated transmission line
Ice modeled as a dielectric material, the equivalent Circuit for a short section of transmission line Coated with ice is shown in figure.
The dielectric properties become sufficiently lossy to generate significant heating.
SKIN EFFECT HEATINGThe crowding of
current near the conductor surface is called skin effect.
Fig 4- Skin effect heating
ACHIEVING UNIFORM HEATING
Fig 5-Combined ice dielectric and skin-effect heating at 60 KHz
Fig 6-Combined ice dielectric and skin-effect heating at 100 kHz, where we estimate the two effects are optimally balanced
ADDITIONAL CONSIDERATION
EMI
CORONA
ADVANTAGESIn this study we get a cost effective approach.This technique is applicable for live line
conductors.It reduces the tension produced by icing.
DISADVANTAGESIt can cause interference with radio
communication system.
CONCLUSIONCombined di-electric heating and skin-effect
heating can be used to achieve uniform heating , and thus dielectric loss takesplace.
The application of 100 kHz electric fields to melting ice on power transmission lines appears promising.
REFERENCES
1. To deice transmission line with 100khz high voltage excitation by Charles R. Sullivan and victor F. Petrenko .Thayer school of engineering.
2. Principles of power system by V.K Mehta and Rohit Mehta.
3. www.brighthub.com