STRUCTURE OF ELECTRICAL POWER SYSTEM

INTRODUCTION:

The generation of electrical energy is nothing but the conversions of various other forms of energy into an electrical energy.The various energy sources which are used to generating electrical energy on the large scale are steam obtained by burning oil ,coal,natural gas,water stored in dams,diesel oil,nuclear power plant and other non conventional energy sources.The electrical power is generated in bulk at the generating station.Unfortunately, electrical power cannot be stored and, therefore, the power station must produce power as and when demanded to meet the requirements of the consumers. On one hand, the power engineer would like that the alternators in the power station should run at their rated capacity for maximum efficiency and on the other hand, the demands of the consumers have wide variations. This makes the design of a power station highly complex.

STRUCTURE OF ELECTRICAL POWER SYSTEM:

The flow of electrical power from the generating station to the consumer is called an electrical power system or electrical supply system.

The important components are,

1.GENERATING STATION 2.TRANSMISSION NETWORK 3.DISTRIBUTION

Variable Load on Power Station

The load on a power station varies from time to time due to uncertain demands of the consumers and is known as variable load on the station

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GENERATING STATION:

A Generating station which is located too far away from the cities and towns.It is generating electrical power at 11 kv. It is required to increase this level for the transmission purpose. A step up transformer is used which steps up the level of voltage to 220 kv.

TRANSMISSION OF POWER:

After generating a power and it is transferred with help of transmission lines and towers ,the transmitted at very long distance.

The scheme is divided into two sections, they are

1.Primary transmission 2.secondary transmission

1.primary transmission:

primary transmission is basically with help of overhead transmission lines.for consumer load demands ,that voltage level is increased to 132 kv,and 220 kv or more with help of step up transformer.This type of transmission is high voltage transmission.The primary transmission is 3 phase 3 wire system.

2.secondary transmission:

The primary transmission line continues via transmission towers till the receiving station.at the receiving station step down the voltage level up to 22 kv or 33 kv with help of step down transformer.There can be more than one receiving station.This power can be transmitted to various substations using over head 3 phase 3 wire system.This is secondary transmission.

DISTRIBUTION OF POWER:

The distribution of power is,power distributed to the local distribution centers with help of distribution.The scheme is divided into two sections. they are,

1.primary distribution 2.secondary distribution

1.primary distribution:

In the distribution side is incoming voltage level is 22kv or 33 kv. So this voltage level is reduced to 6.6 kv,3.3 kv as per the consumer needs with help of step down transformer.It uses the 3 phase 3 wire underground system and power is transmitted to the local distribution centers.So primary distribution is called high voltage distribution.

2.secondary distribution :

At the local distribution centers ,there are step down distribution transformer.The voltage level is 6.6 kv is reduced to 400 v using distribution transformers and also reduced to 230 v.Then finally power can be distributed to consumers with help of distributors and service mains to the consumers.This uses 3 phase 4 wire system.So it is called secondary distribution or low voltage distribution .