Combined operation of different power plants PREPARED BY : Priyanka Grover Btech (EE) SBSSTC,FZR

Combined operation of different power plant  The different types of power plants are located in places best suited to each type-  Hydro-electric power plants are developed only at sites where a huge quantity of water is available at sufficient head, and where storage of water is possible by use of dams in naturally favorable positions  Where as steam, nuclear and diesel power plants can be located at or near the load centers.  In order to have most economic operation and ensure optimum utilization it becomes necessary to operate various power plants located in region in an integrated system. For this purpose all the power plants are connected together, (the system is called the interconnected system) and centrally supervised and controlled.

Cont...  Proper coordination of the generation of electrical power in a group of power plants connected to a common grid system leads to considerable saving as compared with the same loads fed from a number of independent power plants.  First of all, it enables the total generating capacity to be reduced, since less spare capacity is required.  secondly, it allows the system to be planed so that the maximum the power plant to be loaded so that the minimum amount of fuel is consumed.

Advantages of combined operation of plants  If several power plants work together to meet the demand of the consumer then the system is known as “Interconnected System” Advantages:  Greater reliability of supply to the consumers.  When one of the stations fails to operate the consumers can be fed from the other stations, thus avoiding complete shut down.  The overall cost of the energy per unit of an interconnected system is less.  There is more effective use of transmission line facilities at higher voltage.  Less capital investment required. 6. Less expenses on supervision, operation and maintenance.

Load Division between power stations  A load duration curve illustrates the variation of a certain load in a downward form such that the greatest load is plotted in the left and the smallest one in the right. On the time axis, the time duration for which each certain load continues during the day is given.

When the load curve has a very high peak value, it is usually supplied for two or more power stations by interconnection. Total load is divided into two parts. A. Base Load B. Peak Load Base load is supplied by one power station and other power station takes care of the peak load.

Requirements of a plant supplying “Base Load”  Minimum operation cost.  Continuous supply of the load.  Capital cost of the plant should be minimum.  Requirement of plant maintenance should be minimum.  Plant should be such that it can easily be located near the load centre.  The no. of operators required should be minimum.

 Low operating cost.  Minimum capital cost.  Capable of quick operations (from cold conditions).  In the case of emergency, the plant should have the capacity to withstand peak load for some time.  Quick response to the change in load.

Hydroelectric Power Plants: Operating cost is minimum Maintenance cost is lower. Initial cost is high Cant be located near to load. Steam Power Plants: Capital cost is more Can be located near to load center. Maintenance requirement is slightly higher. Diesel Power Plants: Due to limited generating capacity, it is not used as base load plant. Nuclear Power Plant: Initial Cost is High Limited availability of fuel, not favoured. Whenever they are constructed they are used as base load plants due to constant supply.

Hydroelectric Plants: (can be considered as peak load plant.) It can be easily started. No fuel required. Nuclear Power Plants: they are not used as peak load plants. Diesel Power Plants: (can be used for peak load plants) Easily start from cold conditions. Number of auxiliaries required is limited, so less maintenance. They have good overload capacity. They have high thermal efficiency therefore less operating cost than steam power plants.

Hydroelectric Plant in combination with Steam Power Plant.  Hydro Electric plants can take up the load quickly and follow the peak variations much better than thermal plants.  When the run-off is sufficient (in monsoons) Hydro plant is used as base load plant and thermal plant is used as peak load plant.  Thermal plant is used as base load plant during the draught period and hydro plant works as peak load plant.

Introduction to pump storage plant  Pumped Storage Power Plants are a special type of power- plants, which work as conventional hydropower stations for part of the time.  When the plants are not producing power, they can be used as pumping stations which pump water from tail race side to the high level reservoir.  The working of the power station can be distinguished as the generating phase when the turbines and generators are electrical power and the pumping phase when the pump and motors are in operation.

Pump storage plant

Pump storage plant in combination with steam power plant  Pump storage plants are used to take up peak load plants and used for short durations.  These plants possesses the following advantages when used in interconnected system : 1. Thermal plants are loaded more economically. 2. A pump storage plant stores the energy and the same supplied when demand arises.

Co-ordination of hydro-electric and gas turbine plants  Hydro power plant is used during base load requirement  Gas turbine plant used to take up the peak load.  The following points are worth noting about gas turbine plant : 1. Normal capacity of plant :10-20 MW 2. Capital cost of plant is less as compared to steam plant 3. High working cost can be compensated by lower fixed charges and low operational and maintenance cost.

Advantages of gas turbine plant over steam power plant  Occupies less space.  Construction and installation can be carried out in smaller period.  Cooling water requirement is less.  Response of gas turbine plant is quick.

Combined operation based power plant project in India  KAWAS POWER PLANT, GUJARAT 1.Capacity – 645MW 2. Combined cycle generation plant (steam + gas turbine plant)

Thank you