Deepak kumar
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This document presents a project report on the study and design of a 66/33/25kV gas insulated substation (GIS) for DMRC New Delhi. It provides details on the components of a GIS like circuit breakers, disconnectors, earthing switches, transformers, cables and monitoring equipment. It includes a single line diagram of the 66/33/25kV GIS substation and specifications of the transformers, circuit breakers and isolators. It also discusses the properties of sulfur hexafluoride gas used for insulation in GIS and compares GIS with air insulated substations.
Deepak kumar
- 1. STUDY & DESIGN OF 66/33/25KV GIS SUBSTATION DMRC NEW DELHI PROJECT REPORT BACHELOR OF ENGINEERING IN ELECTRICAL ENGINEERING UNDER THE SUPERVISION OF SHEERAZ KIRMANI ASST. PROFFESOR FACULTY OF ENGG.&TECHNOLOGY JAMIA MILLIA ISLAMIA PRESENTED BY NEW DELHI-110025 DEEPAK KUMAR(11BE108) GANESH KUMAR (11BE116)
- 2. INTRODUCTION GAS INSULATED SUBSTATIONS • GAS INSULATED USES SULFUR HEXAFLUORIDE (SF6) • WHICH HAS A SUPERIOR DIELECTRIC PROPERTIES USED AT MODERATE PRESSURE. • IN GAS INSULATED SUBSTATION THE HIGH VOLTAGE CONDUCTORS, CIRCUIT BREAKER INTERRUPTERS,SWITCHES,CURRENT TRANSFORMER ,VOLTAGE TRANFORMER AND LIGHTINING ARRESTERS ARE ENCAPSULATED IN SF6 GAS INSIDE GROUNDED METAL ENCLOSURES. • THE GAS INSULATED SUBSTATION IS PREFERRED FOR LOCATIONS SUCH AS LARGE CITIES AND TOWNS, • UNDER GROUND STATIONS,AND MOUNTAINS AND VALLEY REGIONS
- 3. It consist of • Bus Bars • Circuit Breakers • Disconnecting Switches • Earthing Switches • Current Transformers • Voltage Transformers • Cable and Boxes • Gas Supply and Gas Monitoring Equipment • Local Control
- 4. Circuit Breaker Under short circuit conditions, however, the current may reach tens of thousands of amperes at a power factor as low as 0.1. It is duty of a circuit breaker to interrupt such currents as soon as possible to avoid equipment damage.
- 5. Disconnectors •Disconnectors or isolators are used for electrical isolation of circuit parts •They are slow acting and operating at off load •Disconnectors must be carefully designed and tested to be able to break small charging current without generating too-high over voltage,
- 6. Earthing Switch Earthing switch is used to earth the live parts during maintenance and during testing. During maintenance although circuit is open still there are some voltages on line , due to which capacitance between line and earth is charged. Before proceeding to maintenance work the voltage is discharged to earth, by closing the earth switch.
- 7. Voltage Transformer Voltage transformer is connected to switchgear with the connecting flanges with a barrier insulator. primary winding is insulated with SF6 gas & connected to high voltage terminal. The primary winding is wounded on the top of the core & secondary windings. secondary winding is connected to the terminals in the external terminal box through a gas tight multiple bushing.
- 8. Current Transformer In the single phase enclosed Core of CT is located outside the enclosure inside for three phase Gas compartment to reduce access of moisture and to suppress gas-tight bushings for secondary connections.
- 9. Cables Compartment 1. Optimized solution for plug-in type power cable connection. 2. Adjustable support structures for minimum requirements for the GIS floor. 3. Fixation to the GIS floor by cemented anchor bolts, no need for special foundation (steel beams….etc)
- 10. TECHNICAL SPECIFICATION ENCLOSURE TYPE : THREE PHASE ENCLOSURE RATED VOLTAGE : 72.5 KV RMS RATED FREQUENCY : 50HZ RATED CURRENT OF 2500 A RMS BUS BAR RATED SHORT TIME : 40 KA RMS,3 SEC CURRENT GUARANTED SF6 GAS : LESS THAN 1% LOSSES PER YEAR
- 11. SINGLE LINE DIAGRAM OF 66/33/25 KV GIS SUBSTATION
- 12. AUXILIARY MAIN TRANSFORMER(66/33 KV,30/45 MVA) DESCRIP TION UNIT ONAN ONAF RATING MVA 30 45 RATED PRIMARY VOLTAGE KV 66 66 RATED SECONDARY VOLTAGE KV 33 33 RATED PRIMARY CURRENT AT 66 KV A 262.43 393.65 RATED SECONDARY CURRENT AT 33 KV A 524.86 787.30
- 13. TRACTION TRANSFORMER(66/25 KV,40/50 MVA) DESCRIPTION UNIT ONAN ONAF RATING MVA 40 50 RATED PRIMARY VOLTAGE KV 66 66 RATED SECONDARY VOLTAGE KV 25 25 RATED PRIMARY CURRENT AT 66 KV A 606.06 757.58 RATED SECONDARY CURRENT AT 33 KV A 1600.00 2000.00
- 14. 66 KV LINE CKT BREAKER DESCRIPTION UNIT CALCULATED SELECTED RATED VOLTAGE KV 66 66 RATED PRIMARY CURRENT AT 66 KV A 1151.22 2000
- 15. 66 KV LINE ISOLATOR DESCRIPTION UNIT CALCULATED SELECTED RATED VOLTAGE KV 66 66 RATED PRIMARY CURRENT AT 66 KV A 1151.22 2000
- 16. PROPERTIES OF SF6 •SF6 does not harm to the ozone layer. •Sf6 gas is chemically stable •Non poisonous •Colourless & heavier than air •Almost water insoluble •Non inflammable
- 17. Comparison bw Gis & Ais
- 18. ADVANTAGES • Main advantage of GIS over AIS is its phase to phase spacing decreases significantly. This is more effective in urban environment where land and its size is at a premium • Gis have no risks for fire & explosion. • They generate no noise & have no radio interference • It offer solutions including -In industrial areas where space & pollution problems -Mountain areas where ice & snow are major problems
- 19. DISADVANTAGES GIS installations tend to be much more expensive that air-insulated installations with the same rating. VFTO during switching operations or earth faults and transient enclosure voltages and particle contamination The Damage Effect Will Also Be Severe Whenever Internal Fault occurs.
- 20. APPLICATIONS • High voltage installations. • Urban installations • Indoor installations
- 21. FUTURE TRENDS IN GAS INSULATED SUBSTATIONS Compact design of switch gear. Use of SF6 circuit breaker cells in the medium high voltage GIS and fewer brakes per pole in high voltage circuit breakers Optimization of GIS design to allow easier maintenance
- 22. CONCLUSION • GIS are necessary for EHV & UHV • some important areas to be studied include. • more conservative designs. • improved gas handling . • Achieving & maintaining high levels of availability requires a more integrated approach to quality control by both users and manufactures