26-05-2012, 12:45 PM
KOTA SUPER THERMAL POWER STATION
KOTA SUPER THERMAL POWER STATION.doc (Size: 241 KB / Downloads: 208)
INTRODUCTION
The “KOTA SUPER THERMAL POWER STATION” is ideally located on the left bank of Chambal River at the upstream of “KOTA BARRAGE”. Thermal power station to produce electrical power for supply undertakings K.S.T.P.S. is designed for ultimate capacity of 1045 MW. First two units of 110MW each, another three units of 210MW each and further the sixth unit of 195MW have been completed.
The state Rajasthan is predominantly rural and agricultural .While Rajasthan mineral sources are immense, its sources for power generation weren’t commensurable with its requirements. The large expense of water, stored by the “barrage” provides, as efficient direct circulation cooling system for the power station thus avoiding installation of cooling towers. For bringing in coal for power station and machinery and equipment etc. a 15Km long private siding from the Gurla Railway Station on Delhi-Bombay broad gauge line has been laid-up to the power station.
GENERATOR
Generator is the main part of thermal power station or any power plant. A generator is a machine which converts mechanical energy into electrical energy.
The generator has gas cooling construction enclosing the stator winding, core and hydrogen coolers .The cooling medium hydrogen is contained within the frame and circulation by fans mounted on either ends of the rotor .The generator is driven by directly coupled steam turbine at a speed of 3000 rpm.
Provision has been made for circulating the cooling water in order to maintain a constant temperature of the coolant i.e. H2 as measured at the fan section side which is in touch with the temperature of the winding, core and other parts as per load.
Each of the 2 units under stage-1 have been provided with BHEL make 3-phase turbo generator rated 137.5 MVA, 11KV, 0.8 pf, 7220 Amp, 3000 rpm and 50 cycles/sec .The generator has closed loop of hydrogen gas system for cooling of the stator and rotor at a pressure of 2.0 atm. is filled in a gas tight outer casing of the generator. H2 gas circulates inside the casing by two single stage rotor mounted fans on either side of the rotor .The heated H2 is in turn cooled by six surface type water coolers axially mounted inside the generator casing .The cooling water is supplied to H2 coolers from the BCW over head tank.
Each generator has terminal led out of its casing and a star point is formed by sorting the neutral side terminals by a sorting bar. The neutral is grounded by a 1-phase 11000/220V, 37.5 KVA. Neutral grounding transformer, whose secondary coil is laminated by laminated strip with mechanical ventilating holes, is connected across a 650V, class 0.4 ohm, 50 kW neutral grounding resistors and relays for protection of generator against stator earth faults and stator in turn faults (rating 1 amp).
The H2 gas inside the generator casing is prevented from leaking in between the rotor and shields, by a continuous oil film maintained between the rotor and sealing rings .The shaft sealing system have two independent oil sources associated pumps, regulators, coolers filters, electrical controls and alarm system. Two independent oil sources are provided for air side and H2 side sealing rings. The oil circuit of the H2 side of the shaft seal is closed and the oil is vacuum treated.
DESCRIPTION OF THE GENERATOR PARTS:-
1. STATOR BODY:-
Armature of a generator formed of laminations having slots on its inner periphery to accommodate armature conductors and is known as stator .The stator body is a totally enclosed gas tight fabricated structure suitably internally to rigidity . The function of stator frame is to contain and support the stator core winding , hydrogen coolers and also path for distribution of cooling hydrogen through the generator .
2. STATOR CORE:-
The rotating magnetic field flow with the core .In order to reduce the magnetizing (eddy) current losses in the active portion of the stator core due to rotation of field structure in between the stator the entire core is built up of thin laminations .The segments are stamped out from CRGO .The core contain several pockets separated by steel spaces for radial cooling of the core by hydrogen.
3. STATOR WINDING:-
The stator has 3 phase double layer, short pitched and bar type of winding having two parallel paths .Each slot accommodates two bars .The lower and upper bars are displaced from each other by one winding pitch and connected at their ends so as to form coil groups .Each bar consists of solid as well as hollow conductors with cooling water passing through the later alternator
4. DISTILLATE HEADER:-
Ring type header, made up of copper are provided separately for distillated inlet and outlet min the stator of turbine side .The headers are support on insulator and insulated from stator body .At turbine side each individual bar is connected with inlet/outlet header .The vent pipe connection are at the top of the both inlet and outlet header .The vent pipes are connected to gas trap desire to measure the extent of hydrogen leakage into water circuit.
5. TERMINAL BUSHING:-
Three phases and six neutral terminals are brought out from the stator through bushings which are capable of withstanding high voltage and provided with gas tight joints .The bushing is assembled and tested for flow, leakage to ensure tightness and continuous flow of water.
6. END SHIELD:-
To make the stator body air tight the end shield are fitted .Gas tightness is achieved by putting a rubber sealing cord .The end shields are made3 in two halves convenience during erection and installation.
7. ROTOR:-
The field structure is the largest & heaviest component of generator and is called the rotor. The rotor houses the static excitation winding and the exciting current is supplied to the rotor through the slip rings & brushes. The rotor shaft is a single piece forging the longitudinal slot for inserting the field winding. The slots are distributed over the circumference so that two field solid poles are obtained .
8. BEARINGS:-
The generator bearings are of pedestal type with spherical seating. It allows self alignment and is supported on a separate pedestal on slip ring side. The bearing has a provision of hydraulic shaft lifting during start up and turning gear operation to eliminate shaft current. Shaft bearing and its pipes are insulated from earth.
9. BRUSH GEAR:-
The current carrying gear assembly is rigidly fixed on the extent part of the bearing pedestal on the exciter side. There are two brushes gear stand for (+) ive and (-) ive supply. The field to stator wdg. Provide the brush gear. The designs of brushes during normal operation condition have low coefficient of friction and are self lubricating.
CONCLUSION
The first phase of Practical Training has proved to be quite fruitful. It provides an opportunity for encounter with such huge machines like wagon tippler, 110MW & 210MW Turbines and Generators.
The architecture of the power plant, the way various units are linked and the way working of whole plant is controlled make the student realize that engineering is not just learning the structure description and working of various machine but the great part is of planning proper management.
It also provides an opportunity to lean low technology used at proper place and time can cave a lot of labor e.g. Wagon tippler (CHP).
But there are few factors that require special mention. Training is not carried to its true spirit. It is recommended that there should be some project specially meant for students where presence of authority should be ensured. There should be strict monitoring of the performance of students and system of grading be improved on basis of work done.
However training has proved to be quite fruitful. It has allowed an opportunity to get an exposure of the practical implementation to theoretical fundamentals.
KOTA SUPER THERMAL POWER STATION.doc (Size: 241 KB / Downloads: 208)
INTRODUCTION
The “KOTA SUPER THERMAL POWER STATION” is ideally located on the left bank of Chambal River at the upstream of “KOTA BARRAGE”. Thermal power station to produce electrical power for supply undertakings K.S.T.P.S. is designed for ultimate capacity of 1045 MW. First two units of 110MW each, another three units of 210MW each and further the sixth unit of 195MW have been completed.
The state Rajasthan is predominantly rural and agricultural .While Rajasthan mineral sources are immense, its sources for power generation weren’t commensurable with its requirements. The large expense of water, stored by the “barrage” provides, as efficient direct circulation cooling system for the power station thus avoiding installation of cooling towers. For bringing in coal for power station and machinery and equipment etc. a 15Km long private siding from the Gurla Railway Station on Delhi-Bombay broad gauge line has been laid-up to the power station.
GENERATOR
Generator is the main part of thermal power station or any power plant. A generator is a machine which converts mechanical energy into electrical energy.
The generator has gas cooling construction enclosing the stator winding, core and hydrogen coolers .The cooling medium hydrogen is contained within the frame and circulation by fans mounted on either ends of the rotor .The generator is driven by directly coupled steam turbine at a speed of 3000 rpm.
Provision has been made for circulating the cooling water in order to maintain a constant temperature of the coolant i.e. H2 as measured at the fan section side which is in touch with the temperature of the winding, core and other parts as per load.
Each of the 2 units under stage-1 have been provided with BHEL make 3-phase turbo generator rated 137.5 MVA, 11KV, 0.8 pf, 7220 Amp, 3000 rpm and 50 cycles/sec .The generator has closed loop of hydrogen gas system for cooling of the stator and rotor at a pressure of 2.0 atm. is filled in a gas tight outer casing of the generator. H2 gas circulates inside the casing by two single stage rotor mounted fans on either side of the rotor .The heated H2 is in turn cooled by six surface type water coolers axially mounted inside the generator casing .The cooling water is supplied to H2 coolers from the BCW over head tank.
Each generator has terminal led out of its casing and a star point is formed by sorting the neutral side terminals by a sorting bar. The neutral is grounded by a 1-phase 11000/220V, 37.5 KVA. Neutral grounding transformer, whose secondary coil is laminated by laminated strip with mechanical ventilating holes, is connected across a 650V, class 0.4 ohm, 50 kW neutral grounding resistors and relays for protection of generator against stator earth faults and stator in turn faults (rating 1 amp).
The H2 gas inside the generator casing is prevented from leaking in between the rotor and shields, by a continuous oil film maintained between the rotor and sealing rings .The shaft sealing system have two independent oil sources associated pumps, regulators, coolers filters, electrical controls and alarm system. Two independent oil sources are provided for air side and H2 side sealing rings. The oil circuit of the H2 side of the shaft seal is closed and the oil is vacuum treated.
DESCRIPTION OF THE GENERATOR PARTS:-
1. STATOR BODY:-
Armature of a generator formed of laminations having slots on its inner periphery to accommodate armature conductors and is known as stator .The stator body is a totally enclosed gas tight fabricated structure suitably internally to rigidity . The function of stator frame is to contain and support the stator core winding , hydrogen coolers and also path for distribution of cooling hydrogen through the generator .
2. STATOR CORE:-
The rotating magnetic field flow with the core .In order to reduce the magnetizing (eddy) current losses in the active portion of the stator core due to rotation of field structure in between the stator the entire core is built up of thin laminations .The segments are stamped out from CRGO .The core contain several pockets separated by steel spaces for radial cooling of the core by hydrogen.
3. STATOR WINDING:-
The stator has 3 phase double layer, short pitched and bar type of winding having two parallel paths .Each slot accommodates two bars .The lower and upper bars are displaced from each other by one winding pitch and connected at their ends so as to form coil groups .Each bar consists of solid as well as hollow conductors with cooling water passing through the later alternator
4. DISTILLATE HEADER:-
Ring type header, made up of copper are provided separately for distillated inlet and outlet min the stator of turbine side .The headers are support on insulator and insulated from stator body .At turbine side each individual bar is connected with inlet/outlet header .The vent pipe connection are at the top of the both inlet and outlet header .The vent pipes are connected to gas trap desire to measure the extent of hydrogen leakage into water circuit.
5. TERMINAL BUSHING:-
Three phases and six neutral terminals are brought out from the stator through bushings which are capable of withstanding high voltage and provided with gas tight joints .The bushing is assembled and tested for flow, leakage to ensure tightness and continuous flow of water.
6. END SHIELD:-
To make the stator body air tight the end shield are fitted .Gas tightness is achieved by putting a rubber sealing cord .The end shields are made3 in two halves convenience during erection and installation.
7. ROTOR:-
The field structure is the largest & heaviest component of generator and is called the rotor. The rotor houses the static excitation winding and the exciting current is supplied to the rotor through the slip rings & brushes. The rotor shaft is a single piece forging the longitudinal slot for inserting the field winding. The slots are distributed over the circumference so that two field solid poles are obtained .
8. BEARINGS:-
The generator bearings are of pedestal type with spherical seating. It allows self alignment and is supported on a separate pedestal on slip ring side. The bearing has a provision of hydraulic shaft lifting during start up and turning gear operation to eliminate shaft current. Shaft bearing and its pipes are insulated from earth.
9. BRUSH GEAR:-
The current carrying gear assembly is rigidly fixed on the extent part of the bearing pedestal on the exciter side. There are two brushes gear stand for (+) ive and (-) ive supply. The field to stator wdg. Provide the brush gear. The designs of brushes during normal operation condition have low coefficient of friction and are self lubricating.
CONCLUSION
The first phase of Practical Training has proved to be quite fruitful. It provides an opportunity for encounter with such huge machines like wagon tippler, 110MW & 210MW Turbines and Generators.
The architecture of the power plant, the way various units are linked and the way working of whole plant is controlled make the student realize that engineering is not just learning the structure description and working of various machine but the great part is of planning proper management.
It also provides an opportunity to lean low technology used at proper place and time can cave a lot of labor e.g. Wagon tippler (CHP).
But there are few factors that require special mention. Training is not carried to its true spirit. It is recommended that there should be some project specially meant for students where presence of authority should be ensured. There should be strict monitoring of the performance of students and system of grading be improved on basis of work done.
However training has proved to be quite fruitful. It has allowed an opportunity to get an exposure of the practical implementation to theoretical fundamentals.