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Modern Techniques in Power plant RUPESH P SHEWARE
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Modern Trends in Power plant

Modern Techniques in Power plantRUPESH P SHEWARE1Thermal Power Plants

Total Installed Capacity as on 31st Dec 2011Total Installed Capacity186654 MWInstalled capacity in MW ( as on 31st Dec2011Installed capacity in %( as on 31st Dec2011)Renewable Installed capacity( MW)In financial year ending 2011 energy breakup DescriptionEnergy ( MU)Domestic131383Commercial44432Agriculture123724Industry181168Railway10064Inters-state12697Others43733Total547201Ex-Bus Generation plant)788355Not Sold241153T&D Loss30.58939183Chapter-III, Table-I, HLP ,Shungru ReportIndia Power StoryPLANTARGET( MW )ACHIEVEMENT ( MW )ACHIEVEMNT ( % )1st1951-19561300110084.62nd1956-19613500225064.33rd1961-19667040452064.2Annual Plan 1966-19695430412075.94th 1969-19749264457949.45th 1974-1979124991020281.6Annual Plan 1979-19802813179964.06th 1980-1985196661422672.37th 1985-1990222452140196.2Annual Plan 1990-19914212277665.9Annual Plan 1991-19923811302779.48th Plan 1992-1997305381642353.89th Plan 1997-2002402451911947.510th Plan 2002-2007411102118051.511th Plan 2007-2012787005206366.2Total282373178785ANNUAL PER CAPITA CONSUMPTION OF ELECTRICITY ( IN KWH ) COUNTRYpopulation ( in million )20012011ICELAND0.322614336583.7USA311.591240612606.93JAPAN127.8275797924.22TAIWAN23.17621510141.75UK62.6457595685.35MALAYSIA28.8627493859.49BRAZIL196.6518452034.32IRAN16982315.24CHINA1344.1310192568.33INDIA1241.49474490.97PAKISTAN176.74413413.57SRILANKA20.87300372.62So What Exactly Is Electricity?Electricity by definition is electric current that is used as a power source!This electric current is generated in a power plant, and then sent out over a power grid to your homes, and ultimately to your power outlets.

So How Is An Electric Current Generated?Electric current generation - whether from fossil fuels, nuclear, renewable fuels, or other sources is usually based on the:

Simple EquationFor Electricity GenerationA Simple AC GeneratorWe noted earlier that Faradays law dictates that if a coil of N turns experiences a change in magnetic flux, then the induced voltage V is given by

If a coil of area A rotates with respect to a field B, and if at a particular time it is at an angle to the field, then the flux linking the coil is BAcos, and the rate of change of flux is given by

23.2

In September of 1831, Michael Faraday made the discovery of Electromagnetic Induction.

Faraday attached two wires to a disc and rotated the disc between the opposing poles of a horseshoe magnet creating an electric current.

What does copper wire and magnets have to do with Electricity?Energy/PowerSources of energy :- There are two main sources of energy. They are conventional and non conventional sources of energy. i) Conventional sources of energy :- are wood, flowing water and fossil fuels (coal, petroleum, natural gas).ii) Non conventional sources of energy :- are solar energy, wind energy, biomass energy, ocean energy (tidal energy, wave energy, ocean thermal energy), geothermal energy, nuclear energy etc. Some sources of energy are renewable like sun, wind, flowing water, ocean, wood, biomass etc. Some sources of energy are non renewable like coal, petroleum and natural gas.

LAYOUT OF THERMAL POWER PLANTBoilerC/MTurbineGeneratorESPASPCHPASH BUNDWTP

Video16Hydro Power Video

Thermal Power Plant Cycle

WIND MILLWIND ENERGY FARM

FIXED DOME TYPE BIOGAS PLANT

SOLAR CELL

SOLAR PANELSSOLAR LAMP

TIDAL ENERGYBoiler Overview

What exactly is the turbine? Turbine is an engine that converts energy of fluid into mechanical energy

The steam turbine is steam driven rotary engine.

Construction of steam turbines

How does the steam turbine work?Impulse stage whole pressure drop in nozzle (whole enthalpy drop is changed into kinetic energy in the nozzle)Reaction stage pressure drop both in stationary blades and in rotary blades (enthalpy drop changed into kinetic energy both in stationary blades and in the moving blades in rotor)

Classification of steam turbinesa) way of energy conversion- impulse turbines- reaction turbines

Advantages of turbines Large power achieved by relatively small sizeHigh efficiencySimple designHigh revolution

Ash handling Plants

DM Plant

New Techniques in Power plant

Boiler Natural Circulation Vs. Once Through System

Rankine Cycle Subcritical Unit1

1 - 2 > CEP work2 - 3 > LP Heating3 - 4 > BFP work4 - 5 > HP Heating5 6 > Eco, WW6 7 > Superheating7 8 > HPT Work8 9 > Reheating9 10 > IPT Work1011 > LPT Work11 1 > CondensingRankine Cycle Supercritical Unit

1 - 2 > CEP work2 2s > Regeneration2s - 3 > Boiler Superheating3 4 > HPT expansion4 5 > Reheating5 6 > IPT & LPT Expansion6 1 > Condenser Heat rejectionBoiler Supercritical TechnolgyWhat is Supercritical Technology? The supercritical technology is the thermodynamic state wherethere is no clear distinction between the Water and Steam phasein the Rankine Cycle Water reaches to steam state at a critical pressure above 22.1 MPaat 374 oC.4Rankine Cycle The efficiency of the thermodynamic process is the heat energyfed into the Rankine cycle is converted into electrical energy. Heat energy input to the Rankine cycle is kept constant, the outputcan be increased by selecting high pressures and high temperatures. The key components are supercritical once through boiler and highpressure & high temperature steam turbine.Generator Excitation

EXCITAIONThe exciter is the "backbone" of the generator control system. It is the power source that supplies the dc magnetizing current to the field windings of a synchronous generator thereby ultimately inducing ac voltage and current in the generator armatureTwo basic kinds of excitors Rotating (Brush and brushless) Static exciters(Shunt and series)The amount of excitation required to maintain the output voltage constant is a function of the generator load. As the generator load increases, the amount ofexcitation increases. Reactive lagging pf loads require more excitation than unity pf loads Leading pf loads require less excitation than unity pf loadsAVR PRINCIPALS OF AUTOMATIC VOLTAGE CONTROL

Voltage transformers provide signals proportional to line voltage to the avr where it is compared to a stable reference voltage. The difference (error) signal is used to control the output of the exciter field. For example, if load on the generator increases, the reduction in output voltage produces an error signal which increases the exciter field current resulting in a corresponding increase in rotor current and thus generator output voltage. Due to the high inductance of the generator field windings, it is difficult to make rapid changes in field current. This introduces a considerable "lag" in the control system which makes it necessary to include a stabilizing control to prevent instability and optimize the generator voltage response to load changes. Without stabilizing control, the regulator would keep increasing and reducing excitation and the line voltage would continually fluctuate above and below the required value. Modern voltage regulators are designed to maintain the generator line voltage within better than +/- 1% of nominal for wide variations of machine load.

Excitaion System

Brushless Exciter BRUSHLESS EXCITATIONWhile brushless excitation system eliminate the need for brushes, commutator & slip-ring.It uses bridge rectifier circuit consists of SCR & diode.The bridge rectifier circuit placed on the rotor.The bridge rectifier circuit rotates with the speed of the rotor.The A.C supply given to the bridge rectifier by the principle of Electromagnetic Induction.Bridge rectifier being represented by a transformation from A.C voltage to D.C voltage.The D.C output of the rotating rectifier is applied to the D.C rotating field of the motorBREAKERS

Air Blast & Oil Circuit Breakers

SF6 & Vacuum Circuit Breakers

Comparison between SF6 & Vacuum breakerCriteriaSF6 BreakerVacuum Circuit BreakerSummated current cumulative10-50 times rated short circuit current30-100 times rated short circuit currentBreaking current capacity of interrupter5000-10000 times10000-20000 timesMechanical operating life5000-20000 C-O operations10000-30000 C-O operationsNo operation before maintenance5000-20000 C-O operations10000-30000 C-O operationsTime interval between servicing Mechanism5-10 years5-10 yearsOutlay for maintenanceLabour cost High, Material cost LowLabour cost Low, Material cost HighReliabilityHighHighDielectric withstand strength of the contact gapHighVery highWhat are Relays?Relays are electrical switches that open or close another circuit under certain conditions.

Relay PurposeIsolate controlling circuit from controlled circuit.Control high voltage system with low voltage.Control high current system with low current.Logic Functions51Relay TypesElectromagnetic Relays (EMRs)EMRs consist of an input coil that's wound to accept a particular voltage signal, plus a set of one or more contacts that rely on an armature (or lever) activated by the energized coil to open or close an electrical circuit.Solid-state Relays (SSRs)SSRs use semiconductor output instead of mechanical contacts to switch the circuit. The output device is optically-coupled to an LED light source inside the relay. The relay is turned on by energizing this LED, usually with low-voltage DC power. Microprocessor Based RelaysUse microprocessor for switching mechanism. Commonly used in power system monitoring and protection.How a Relay Works

Sold-State Relay

54These relays were developed with the advent of transistors,operational amplifiers etc. Their functionality is throughvarious operations like comparators etc. Their advantages areMore flexible.Self checking facility.Less power consumption and low burden.Improved dynamic perfomance characteristics.High seismic withstand capacity.Reduced panel space.Solid State Relays

Numeric RelaysOperation of a numerical relay involves analog to digitalconversion of voltage and currents obtained from VT andCTs. These samples are fed to the microprocessor or DSPwhere the protection algorithms process these signals andnecessary decisions are taken.Numerical Relays

Its advantages areMaximum flexibility.Provides multiple functionality.Self checking and communication facility.It can be made adaptive.AdvantageWhy A System Needs Protection?

There is no fault free system.It is neither practical nor economical to build a fault free system.Electrical system shall tolerate certain degree of faults.Usually faults are caused by breakdown of insulation due to various reasons: system aging, lighting, etc.Electrical Faultsmajority are phase-to-ground faultsphase-to-phase phase-phase-phase double-phase-to-groundAdvantages for Using Protective RelaysDetect system failures when they occur and isolate the faulted section from the remaining of the system.

Mitigating the effects of failures after they occur. Minimize risk of fire, danger to personal and other high voltage systems.

Protective Devices ComparisonRelaysCircuit BreakersFusesAcquisitionDetectionActivationActuationAdvantages/DisadvantagesElectromagnetic Relays (EMRs)SimplicityNot expensiveMechanical WearSolid-state Relays (SSRs)No Mechanical movementsFaster than EMRNo sparking between contactsMicroprocessor-based RelayMuch higher precision and more reliable and durable. Improve the reliability and power quality of electrical power systems before, during and after faults occur.Capable of both digital and analog I/O.Higher cost

63Advantages of PLCs Less wiring. Wiring between devices and relay contacts are done in the PLC program. Easier and faster to make changes. Trouble shooting aids make programming easier and reduce downtime. Reliable components make these likely to operate for years before failure.

INTRODUCTION TO PLCS6465Programmable Logic Controllers( Definition according to NEMA standard ICS3-1978)A digitally operating electronic apparatus which uses a programming memory for the internal storage of instructions for implementing specific functions such as logic, sequencing, timing, counting and arithmetic to control through digital or analog modules, various types of machines or process.

66PLC Size1. SMALL- it covers units with up to 128 I/Os and memories up to 2 Kbytes. - these PLCs are capable of providing simple to advance levels or machine controls.2. MEDIUM- have up to 2048 I/Os and memories up to 32 Kbytes.3. LARGE- the most sophisticated units of the PLC family. They have up to 8192 I/Os and memories up to 750 Kbytes.- can control individual production processes or entire plant.67Major Components of a Common PLCPROCESSOR POWERSUPPLYI MN O P D U UT L E

O M U OT DP UU LT E

PROGRAMMING DEVICEFrom SENSORS

Pushbuttons,contacts,limit switches,etc.ToOUTPUT

Solenoids, contactors, alarmsetc.

SCADA ( Supervisory Control & Data Acquisition System )Computer Control Networks

3. DCSMost comprehensiveLocal Control Unit: This unit can handle 8 to 16 individual PID loops. Data Acquisition Unit: Digital (discrete) and analog I/O can be handle. Batch Sequencing Unit: This unit controls a timing counters, arbitrary function generators, and internal logic.Local Display: This device provides analog display stations, and video display for readout.Bulk Memory Unit: This unit is used to store and recall process data.

DCS Elements-1General Purpose Computer : This unit is programmed by a customer or third party to perform optimization, advance control, expert system, etc Central Operator Display: This unit typically contain several consoles for operator communication with the system, and multiple video color graphics display unitsData Highway : A serial digital data transmission link connecting all other components in the system. It allow for redundant data highway to reduce the risk of data lossLocal area Network (LAN) DCS Elements-2DDC

DCS

Access a large amount of current information from the data highway.

Monitoring trends of past process conditions.

Readily install new on-line measurements together with local computers.

Alternate quickly among standard control strategies and readjust controller parameters in software.

A sight full engineer can use the flexibility of the framework to implement his latest controller design ideas on the host computer.Advantages of DCSHoneywellFisher-RosemontBailyFoxboroYokogawaSiemenDCS VendorsCooling TowersCooling towers are heat removal devices used to transfer process waste heat to the atmosphere. Cooling towers may either use the evaporation of water to remove process heat and cool the working fluid to near the wet-bulb air temperature or, in the case of closed circuit dry cooling towers, rely solely on air to cool the working fluid to near the dry-bulb air temperature.Types of Coolong TowerWith respect to drawing air through the tower, there are three types of cooling towers:Natural draft Utilizes buoyancy via a tall chimney. Warm, moist air naturally rises due to the density differential compared to the dry, cooler outside air. Warm moist air is less dense than drier air at the same pressure. This moist air buoyancy produces an upwards current of air through the tower.Mechanical draft Uses power-driven fan motors to force or draw air through the tower. Induced draft A mechanical draft tower with a fan at the discharge (at the top) which pulls air up through the tower. The fan induces hot moist air out the discharge. This produces low entering and high exiting air velocities, reducing the possibility of recirculation in which discharged air flows back into the air intake. This fan/fin arrangement is also known as draw-through. (see Image 3)Forced draft A mechanical draft tower with a blower type fan at the intake. The fan forces air into the tower, creating high entering and low exiting air velocities. The low exiting velocity is much more susceptible to recirculation. With the fan on the air intake, the fan is more susceptible to complications due to freezing conditions. Another disadvantage is that a forced draft design typically requires more motor horsepower than an equivalent induced draft design. The benefit of the forced draft design is its ability to work with high static pressure. Such setups can be installed in more-confined spaces and even in some indoor situations. This fan/fill geometry is also known as blow-through. (see Image 4)Fan assisted natural draft A hybrid type that appears like a natural draft setup, though airflow is assisted by a fan.

Induced Draft Cooling Tower

Natural Draft Cooling Tower

Chimney

Bus Transfer SchemeThere are two types of Bus transfers 1) Transfer Bus scheme2) Breaker and half Transfer schemeTransfer bus

Breaker & HalfBLine-ILine-IBusMessage Why do we want cheap and abundant Electricity in India ?The answer is that without cheap and abundant electricity no effort for the Industrialization of India can succeed. Ask Another question Why is industrialization necessary?We want industrialization in India as the surest means to rescue the people from eternal cycle of poverty in which they are caughtDr.B.R.Ambedkar. ( Dr.Ambedkar , Labour Memebers address to the first meeting of Reconstruction Policy Committee on Public Work and electric Power , New Delhi , Oct 25 1943)

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