Electrical Engineering Fifth Semester Electrical Power- I Electrical Engineering Fifth Semester

Contents Generator Thermal power plant Hydro power plant Diesel Power Plant Nuclear Power Plant Comparisons Cost of Electrical Energy Demand, Diversity and Load factor

Generator Generator convert mechanical energy into electrical energy Michael Faraday 1791-1867invented the generator in 1831 Prime mover /turbine is used to move generator

Thermal power plant

Thermal power plant Coal: In a coal based thermal power plant, coal is transported from coal mines to the generating station. Generally, bituminous coal or brown coal is used as fuel. The coal is stored in either 'dead storage' or in 'live storage'The coal from live storage is first crushed in small particles and then taken into pulverizer to make it in powdered form Boiler: The mixture of pulverized coal and air (usually preheated air) is taken into boiler and then burnt in the combustion zone Superheater:steam produced in the boiler tubes is superheated to about 540 °C in the superheater. The superheated high pressure steam is then fed to the steam turbine.  Economizer: An economizer is essentially a feed water heater which heats the water before supplying to the boiler.  Air pre-heater: The primary air fan takes air from the atmosphere and it is then warmed in the air pre-heater. Steam turbine: High pressure super heated steam is fed to the steam turbine which causes turbine blades to rotate. Condenser: The exhausted steam is condensed in the condenser by means of cold water circulation Feed water pump: The condensed water is again fed to the boiler by a feed water pump

Hydro power plant

Hydro Power Plant Dam and Reservoir: The dam is constructed on a large river in hilly areas to ensure sufficient water storage at height. The dam forms a large reservoir behind it Control Gate: Water from the reservoir is allowed to flow through the penstock to the turbine. The amount of water which is to be released in the penstock can be controlled by a control gate Penstock: A penstock is a huge steel pipe which carries water from the reservoir to the turbine surge tank provides excess water needed when the gates are suddenly opened to meet the increased load demand Types Of Hydro-Power Plants Conventional Plants: Pumped Storage Plant: Run-Of-River Plant:

Diesel Power Plant

Diesel Power Plant Fuel supply system there are one storage tank strainers, fuel transfer pump and all day fuel tank. Storage tank where oil in stored. Strainer : This oil then pump to dry tank, by means of transfer pump. Air intake to the engine for fuel combustion. It consists of a pipe for supplying of fresh air to the engine. Filters are provided to remove dust particles from air The exhaust gas is removed from engine, to the atmosphere by means of an exhaust system. A silencer is normally used in this system to reduce noise level of the engine The pump circulates water through cylinder and head jacket. The water takes away heat from the engine and it becomes hot Lubricating system minimize Starting a diesel engine, initial rotation of the engine shaft is required. Until the firing start and the unit runs with its own power. For small DG set, the initial rotation of the shaft is provided by handles but for large diesel power stations the wear of rubbing surface of the engine

Nuclear Power Plant

Nuclear Power Plant In the reactor heat is produced due to the happening of the nuclear fission in the fuel. At the time of fission process high amount of heat must be generated Nuclear fuels are Plutonium . The movements of refining, mining, purifying disposing of nuclear fuel together create the nuclear fuel cycle. fuels are hit by the neutrons Moderator is used to reduce the kinetic energy of the fast moving neutrons to slow down the moving neutrons. moderators used are beryllium, graphite and heavy water The losses are decreased by surrounding the core reactor by a material which is known as reflector. They are made up of beryllium and graphite. The exhausted steam must be converted into the water in the condenser through cooling COMPARISION OF VARIOUS PLANT……………….cont..

Cost Of Electrical Energy Fixed cost, Semi-fixed cost, Running or operating cost. Fixed Cost remains constant independent of the maximum demand, the plant capacity and the energy generated. It includes Annual charges of the central organization management Salary of the employees (usually higher officials) Interest on the land costs Semi-fixed costs are independent of the energy (kWh) generated but depend upon the maximum demand. Higher the max demand, the greater the semi-fixed costs. Interest and depreciation on the capital costs  interest of this loaned amount  salaries of the management and other (clerical) staff

Running Or Operating Cost a) Running charges will depend mainly upon the energy (in units or kWh) generated by the plant. b) Cost of fuel: This cost, of course, varies with the type of plant. It is lower in thermal (coal based) plants than nuclear plants. However, for hydroelectric plants (HPS), this cost is nil. c) Cost of maintenance and repairs: As a plant ages, wear and tear occur, and maintenance is needed. The wear and tear of the plant necessitate the use of lubricating oil which has its own cost. d) Salaries of the operating staff: The higher the size (capacity), the more the number of operating personnel required.

Demand factor Demand Factor = Maximum demand / Total connected load For example, an over sized motor 20 Kw drives a constant 15 Kw load whenever it is ON. The motor demand factor is then 15/20 =0.75= 75 %. Demand factor is always < =1. Demand Factor is always change with the time to time or hours to hours of use and it will not constant. The connected load is always known so it will be easy to calculate the maximum demand if the demand factor for a certain supply is known at different time intervals and seasons. The lower the demand factor, the less system capacity required to serve the connected load.

Diversity factor Diversity Factor = Sum of Individual Maximum Demands / Maximum Demand of the System. Diversity Factor = Installed load / Running load. The diversity factor is always >= 1. Diversity Factor is always >1 because sum of individual max. Demands >Max. Demand. In other terms, Diversity Factor (0 to 100%) is a fraction of Total Load that is particular item contributed to peak demand. 70% diversity means that the device operates at its nominal or maximum load level 70% of the time that it is connected and turned ON. It is expressed as a percentage (%) or a ratio more than 1. If we use diversity value in % than it should be multiply with Load and if we use in numerical value (>1) than it should be divided with Load. In general terms we can say that diversity factor refers to the percent of time available that a machine. 70% diversity means that the device operates at its nominal or maximum load level 70% of the time that it is connected and turned ON. Greater the diversity factor, lesser is the cost of generation of power.

Load Factor Load Factor=Actual Load / Full Load It is the ratio of actual kilowatt-Hours used in a given period, divided by the total possible kilowatt -hours that could have been used in the same period at the peak KW level. Load Factor = ( energy (kWh per month) ) / (  peak demand (kW) x hours/month ) In other terms Load factor is defined as the ratio of Average load to maximum demand during a given period. Load Factor= Average Load / Maximum Demand during given Time Period The Load factor is always <= Motor of 20 hp drives a constant 15 hp load whenever it is on.  The motor load factor is then 15/20 = 75%

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