Electrical Power system basics

What is the basic Electrical Power System ? |Power transmission definition | What is the basic structure/overview of Electrical Power System ? | Explain energy transmission system

Basic Electrical Power System consist of three main components Generation, Transmission and  Distribution. In Power System the electrical energy is generated from Nuclear energy, Solar, Wind, Petroleum, Coal, etc. and then transmitted through transmission line to distribution station from there to load/consumers.

Main Components of electrical Power System :

1. Generating station

2. Transmission line

3. Distribution station

 

Basic Overview/structure of electricity transmission system:

Electrical energy generated at generating station by synchronous generator. The generating voltages are generally 11 kV and 33 kV. This voltage is then stepped up by a step-up transformer up to 132 kV, 220 kV, 400 kV for transmission over long distances. Again this high voltages are brought down to sub-transmission level i.e. 66 kV  to supply large consumer and further stepped down for primary distribution  i.e. 33 kV, 11 kV. For secondary distribution level voltage is brought down to 400 V for 3-Φ and 230 V for 1-Φ for residential and commercial used.

Single line diagram

Basic Power System Overview

 

1. Generating station:

Power generation plants produce the electrical energy that is ultimately delivered to consumers through transmission lines, substations, and distribution lines. Generation plants or power plants consist of a three-phase generator (s), the prime mover, energy source, control room, and substation. The generating station consist of one large or many small Generators which convert mechanical energy into the electrical energy. These generators are of different types for as per the resources used for generation.

a. Steam turbines

• Fossil fuels (coal, gas, oil)
• Nuclear
• Geothermal
• Solar-heated steam

b. Hydro turbines

• Dams and rivers
• Pump storage

c. Combustion turbines

• Diesel
• Natural gas
• Combined cycle

d. Wind turbines

e. Solar direct (photovoltaic)

2. Transmission line:

The transmission system may be divided into primary and secondary (sub-transmission) transmission system. Transmission level voltages are in the range of 66 kV to 400 kV (or higher).

The primary transmission line voltage is in the range of 132 kV, 220 kV and 400 kV. And the secondary (sub-transmission) transmission voltage is in the range of 66 kV.

3. Distribution station:

Distribution system can be divided into primary and secondary distribution system. Most of the distribution networks operate radially for less short circuit current and better protective co-ordination.

Distribution consists of a step-down transformer (e.g. 132/11 kV or 66/11 kV or 33/11 kV) at a bulk supply point feeding a number of lines with varying length from a few hundred meters to several kilometers. Several 3 phase step-down transformers, e.g. 11 kV/400 V are spaced along the feeders and from these, three-phase four wire networks of consumers are supplied which give 230 volt single phase supply to domestic loads.

Important Tips : 

• Generating stations are interconnected by the lines.
• Transmission lines, when interconnected with each other, becomes transmission networks.
• The combined transmission and distribution network is known as "Power Grid".