Why Is Synchronous Generator Used for Generating Electricity

by Starlight Generator dieselgeneratortech

There are a few reasons why synchronous generators are used to supply electric power

1. Constant Voltage.

2. Constant frequency.

3. Capability to deliver active as well as reactive power.

Appropriate synchronization between all alternators to an infinite bus bar (V=1<0 p.u constant).

Various generators from across the country synchronize with this infinite bus which can supply electric power from anywhere in the country. This has flexibility to increase the number of generator set synchronized with the infinite bus bar.

On the other hand if we use induction generators instead of synchronous generators, there will be two aspects:

1. Reactive power requirement of I.G

2. Harmonic content in output power spectrum.

The I.G requires reactive power for its operation which needs to be provided either by capacitor banks or I.G. units must be connected to a stable grid where reactive power is available. If we use I.G’s for generation of electric power we will have severe active and reactive power issues and hence voltage will have imbalance. If we have to install capacitor banks, there will be huge costing in installation of these equipment.

The output frequency of Induction Generator is variable which will create uncertainties in deciding ratings for electric equipment and load side equipment will have problems with varying frequency. To deal with this we need to convert Variable AC power to DC power and back to Fixed frequency AC power using power electronic equipment which induces high amount of harmonic content in output spectrum which is undesirable and design of Harmonic filters and their implementation will increase cost.

Hence Synchronous Generator is used to supply power which are mainly large generation units like thermal, hydro, nuclear and Gas power plant etc. Induction Generators are installed mainly in wind power plants and small hydro power plants.

Induction generator and synchronous generator both are used for large scale production of electricity while we use DC generators for few specific requirements. Moreover, DC generators need carbon brushes for load current to flow and therefore we can't use them for large scale production also we may have to convert the same into AC which will be a more tedious task. So, DC is not at all feasible.

Induction generator can be used and is used in wind turbines as mentioned appreciably well in one of the answers. But we can't get reactive power from induction generator and therefore we need an alternate power source to run our system.

In case of synchronous generator we can generate active as well as reactive power and therefore it meets our requirements completely and individually.

But synchronous generator has issues as well. They have stability problem. Also, frequency also varies with load variations. Synchronous generator is widely used in a diesel generator or industrial equipment.