Ntpc Plant Dadri(2003) Plain

Name : Ankit Mishra Kamna Sharma

Branch : Electrical & ElectronicsCollege : VITSRoll No. : 0622321007 0622321020

Contents NTPC Dadri and its features Types of plant-- Gas plant Thermal plant Electrical components of NTPC-- Transformers Cooling towers Turbine Switchyard & its

components HVDC transmission View of NEW cooling tower

About NTPC Dadri… NTPC’s Dadri plant is the only one in India to house Gas-

based as well as Coal-based generating units. The plant’s combined capacity is 1669MW (840MW on coal & 829MW on gas).

The coal-based station’s boiler can be fired using 100% furnace oil as well. The Gas station has two modules, consisting of four 130.4MW gas turbines and two 154.5MW steam turbines.

The station has the largest switchyard in India, with power handling capacity of 4500MW.

As a part of the infrastructure for the Commonwealth Games, the station is adding coal based capacity of 980MW consisting of two units of 490MW each.

The plant is spread over 2665 acres, making it one of the largest sites on India with 1130+ employees working and they have been given well accomodation over there.

Acquisition of Dadri Plant Area…

GAS PLANT… Plant receives gas through HBJ pipeline, originating

at Hazira.

Works on combined cycle having very high efficiency of 48.33% as opposed to 32% offered by open cycle.

Main fuel is Natural gas.

Ganga canal provides source of cooling water, if closed, then tube-wells serves this purpose.

Gas turbine plants use the dynamic pressure from flowing gases to directly operate the turbine. Natural-gas fuelled turbine plants can start rapidly and so are used to supply "peak" energy during periods of high demand, though at higher cost than base-loaded plants.

SALIENT FEATURES :i) Type of Station : Combined Cycle Power Plant

ii) Station Capacity : 817 MW

iii) Fuel : Main - Natural GasAlternate fuel – HSD Source,

iv) Consumption : Through HBJ Pipe Line 4.0 MCMD

v) Cooling Water source : Upper Ganga Canal Dehraheadwork. During closer of UGC through network of tube wells.

vi) Startup Power : Black Start DG set 2.6 MVA capacity.

vii) Heat rate- open cycle : 2692 Kw / KwhCombined cycle : 1748 Kw / Kwh

Viii) Efficiency

Open cycle : 32%Combined cycle : 48.33%

Some Photographs of GAS PLANT…

Thermal plant In thermal power stations, mechanical power is

produced by a heat engine that transforms thermal energy, often from combustion of a fuel, into rotational energy. Most thermal power stations produce steam, and these are sometimes called Steam power stations.

Main fuel used in Dadri plant is COAL.

The coal unit receives coal from north Karanpura mines located in Jharkhand, almost 1400 km from Dadri.

The coal is fed through a rail link. NTPC has a dedicated ralway siding that connects Dadri station and the plant.

Transformer The transformer is based on two principles: firstly, that an

electric current can produce a magnetic field (electromagnetism) and secondly that a changing magnetic field within a coil of wire induces a voltage across the ends of the coil (electromagnetic induction).

Changing the current in the primary coil changes the magnetic flux that is developed. The changing magnetic flux induces a voltage in the secondary coil.

Major Transformers in Power Station…Unit Transformer… Inter Connecting

Transformer The unit transformers

for the gas plant are 4 in number(one for each generator).

Used to step up 10.5KV, produced by generator, to 220KV that enters the switchyard.

These are 166MVA transformers manufactured at BHEL and type of cooling is OFAF.

This transformer is used to step up the volt from 200KV to 400KV for transmission purpose.

There are 2 ICTs in the NTPC plant switchyard. They differ from other transformers in a way as they have a different unit for each phase.

Manufactured at BHEL,they have rating of 167MVA & the cooling is of type OFAF.

Cooling of Transformer… Heat is produced in the windings due to current flowing in

the conductors & in the core on account of eddy currents and hysteresis losses.

In dry transformer, heat is dissipated directly to the atmosphere but in Oil immersed type, heat is given out by Thermo-syphon action.

Thermo-syphon action refers to the circulating currents set up in a liquid because of temperature difference between one part of the container and the other.

When oil becomes hot , it becomes lighter and therefore rises up, drawing colder oil to go below. The rising current of oil takes away the heat from the oil surfaces to the top of the tank, from there it passes down the radiator tubes where the heat is radiated out to the atmosphere.

In Power plant, the coolant used in transformers are… ~Polychlorinated biphenyls ~Fuorinated hydrocarbons ~Silicone -based oils,

Cooling towers Cooling towers are heat removal devices used to

transfer process waste heat to the atmosphere.

Height can be up to 200 m tall and 100 m in diameter

Heat transfer method:-

Wet cooling towers or simply cooling towers operate on the principle of evaporation.

Dry coolers operate by heat transfer through a surface that separates the working fluid from ambient air, such as in a heat exchanger. They do not use evaporation.

Fluid coolers are hybrids that pass the working fluid through a tube bundle, upon which clean water is sprayed and a fan-induced draft applied.

Mechanism of Cooling Tower

Turbine… Steam turbine extract heat from

steam and converts it into mechanical work by expanding the steam from high pressure to low pressure.

Conventional turbines consist of shaft with blades mounted upon it. This looks very much like closely spaced propeller blades that are pushed by pressure exerted through gas or air which causes the shaft to rotate.

These turbine shaft/blade assemblies can weigh as much as 40 tons and spin at 3,600 rpm.

The Tesla turbine is a completely different machine. Rather than depending upon blades, it depends on centrifugal force created by adhesion of the steam/gas to large, smooth surface areas of closely spaced rotor disks.

Steam Turbine Characterstics…

Major NTPC Plants of India

April 8, 2023PMI Revision 00 21

Diesel Generator… A diesel generator is the

combination of a diesel engine with an electrical generator (often called an alternator) to generate electric energy.

The use of DG is to provide startup power during black out resulting in the shutdown of the whole plant.

It is capable of supplying startup power for one gas turbine.

DG set is always kept in pre-lubricated condition and start with air motor.

It takes 15 seconds from initiations of start signal.

Switchyard(Sub-stations)The switchyard may be a step-up or step-down

sub-station. In DADRI NTPC, the 220KV gas switchyard consists of…

Ckt breaker : 10nos Isolator with two earth switch 1250A : 6nos Isolator with two earth switch 2500A : 2nos Isolator without earth switch staggered type: : 22nos Current transformer : 27nos Post insulator : 74nos Current transformer with extended : 3nos current Lightening arresters : 18nos

Switchyard Main components Isolators : These are used to remove the excess volt

remaining on the bus and bays after the operating of CB.

Isolator can’t operate unless the breaker or the corresponding switch is open.

Current transformers : It is placed for measuring current and for differential protection of the transformers.

They have highest system temperature of 945 with rated primary current of 1600A.

Lightening arresters : These are devices used for the protection of electrical components,in the switchyard, against surge or lightening strikes.

Switchyard

HVDC TRANSMISSION…It is a low loss mode of transmission used to

transmit power at very high voltages of +500KV.

A HVDC line runs from Rihand to Dadri with capacity of 1500 MW.

The transmission loss is about 3% as compared to 8% in AC transmission.

Another advantage is that it can be used to transmit power in both ways i.e. by converting DC AC and vice-versa.

The power after conversion to AC is transmitted from the combined switchyard to all sub-stations.