Electrical Energy is one of the most basic needs for the economic development and progress of a country. Various functions that are vital to present-day living may halt due to unavailability of electric energy.
The energy supply system is called Power System. The role of electricity in the development of modern civilization cannot be estimated. The economy of a country depends directly on the availability of surplus electric energy. In fact, per-capita income of a country is directly proportional to the energy consumption per person. The greater the per capita consumption of energy in a country, the higher is the standard of living of its people.
Energy exists in different forms in nature but the most important form is the electrical energy. The modern society is so much dependent upon the use of electrical energy that it has become a part and parcel of our life. In this article, we shall focus our attention on the general aspects of electrical energy, its generation, transmission and distribution system which is known as Power System.
What is a Power System?
Electricity is generated at central power stations and then transferred to loads (i.e, Domestic, Commercial and Industrial) through the transmission and distribution system. A combination of all these systems is collectively known as an Electric Power System.
A power System is a combination of central generating stations,
Electric Energy Supply System
The transmission of electric power from a power station to consumers’ premises is known as
theelectric supply system.
An electric supply system consists of three principal components viz., the power station, the transmission lines and the distribution system. Electric power is produced at the power stations which are located at favourable places, generally quite away from the consumers. It is then transmitted over large distances to load centres with the help of conductors known as transmission lines. Finally, it is distributed to a large number of small and big consumers through a distribution network, supply system can be broadly classified into (i) d.c. or a.c. system (ii) overhead or underground system.
Nowadays, 3-phase, 3-wire AC system is universally adopted for generation and transmission of electric power as an economical proposition. However, distribution of electric power is done by 3-phase, 4-wire a.c. system. The underground system is more expensive than the overhead system. Therefore, the overhead system is mostly adopted for transmission and distribution of electric power.
Typical AC Power Supply in a Power System
The large network of conductors between the power station and the consumers can be broadly divided into two parts viz., transmission system and distribution system. Each part can be further sub-divided into two—primary transmission and secondary transmission and primary distribution and secondary distribution. In Fig. 2, the layout of a typical AC power supply scheme in a power system is shown by a single line diagram. It may be noted that it is not necessary that all power schemes include all the stages shown in the figure. For example, in a certain power scheme, there may be no secondary transmission and in another case, the scheme may be so small that there
Energy is generated (transformed from one to another) at the generating stations. Generating stations are of different type, for example, thermal, hydel, solar power
In Fig. 2, G.S. represents the generating station where electric power is produced by 3-phase alternators operating in parallel. The usual generation voltage is †11 kV. For economy in the transmission of electric power, the generation voltage (i.e., 11 kV) is stepped
It may appear advisable to use the highest possible voltage for transmission of electric power to save conductor material and have other advantages. But there is a limit to which this voltage can be increased. It is because the increase in transmission voltage introduces insulation problems as well as the cost of switchgear and transformer equipment is increased. Therefore, the choice of proper transmission voltage is essentially a question of economics. Generally, the primary transmission is carried at 66 kV, 132 kV, 220 kV or 400 kV.
The electric power at 132 kV is transmitted by
The primary transmission line terminates at the receiving station (RS) which usually lies
The secondary transmission line terminates at the sub-station (SS) where
In the last stage in a Power System, the electric power from
Fig. 6 shows the elements of low voltage distribution system. Feeders (SC or SA) radiating from the distribution sub-station (DS) supply power to the distributors (AB, BC, CD and AD). No consumer is given direct connection from the feeders. Instead, the consumers are connected to the distributors through their service mains.
We hope you’ve got the basic idea of the power system, its basic components and their functioning. You may also want to read our articles on the implementation of protection schemes in ETAP and Load flow analysis of a power network.