21-04-2012, 04:43 PM
GAS TURBINE
Switchgear& protection[1].doc (Size: 577.5 KB / Downloads: 168)
INTRODUCTION
DESCRIPTION OF STAGE-1:
The generation capacity of stage 1 is 100MW.This comprises of two gas turbines each of 33MW capacity and steam turbine with a generating capacity of 34MW.
GAS TURBINE:
A gas turbine power plant consists of a gas turbine with compressor mounted on the same shaft or coupled to the turbine, the combustion chamber, an alternator coupled to the turbine itself and auxiliary chamber such as starting device auxiliary lubrication pumps, oil system, fuel & duct system etc.
The compressor (17stage axial) from the atmosphere sucks in the air through the filter, which removes dust from the air. At the output of the compressor the air is available with high pressure. The compressor air is fed into the combustion chamber. Fuel (natural gas) is injected into the combustion chamber and burnt in the steam of air supplied from the compressor. The products of the combustion comprising of mixture of gases at high pressure & temperature (around 1500c) are passed through the gas turbine.
SINGLE LINE DIAGRAM
There are four outgoing feeders namely Bommuru-II & III and Nidadavolu and K Kota at 220kv bus for stage-II. This 220kv is step down to 11kv by two transformers one is of gas turbine and other is of steam turbine. This 11kv is step down to 6.6kv by two unit auxiliary transformers one is of gas turbine and other is of steam turbine.
This MV (medium voltage-6.6kv) supplies power to all auxilaries that are connected to 6.6kv bus. These Auxilaries contains motors and three transformers which step down MV to 415v(LV).
NORMAL OPERATION OF PLANT:
Under normal start up of the plant, the auxiliary power is derived from 220KV bus in the switchyard.MV-I is energised through GTG Main Transformer and GTG Unit transformer by closing circuit breakers 52T1 & 52MUT1.Similarly MV-2 is energized through STG Main transformer and STG Unit transformer by Closing breakers 52T2 & 52MUT2.Bus tie breaker, 52MBT is kept open and Is interlocked with 52MUT1 & 52MUT2 such that tie breaker cannot close when 52MUT1 & 52MUT2 are closed.
Breaker 52MBT can be closed only if atleast one of the MV in corner breakers are open.LV-1 and LV-2 are energized through auxiliary transformers 1 & 2 by closing breakers 52MAT1,52LAT1 and 52MAT2, 52LAT2 respectively.
CONCLUSION
The mini project opportunity given to us by authorizes APGPCL& APGENCO at their gas turbo power station, vijjeswaram at the request of our SASI INSTITUTE OF TECHNOLOGY & ENGINEERING TADEPALLIGUDEM is much useful in the mini project we tried link up between theory that we had studied and practical things going on in particular to Power Generation and Protections. We also studied how the electricity is generated in the combined cycle power plant and also about electrical protections.